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tda1572 oscillator configuration
Has anybody used the oscillator section of the tda1572 with a crystal type
of configuration. I looked at the tda1072 application note in one of my old data books, and I don't see how that circuit would even oscillate. I know that it can be done, because the Linn Kudos FM/AM tuner does this with the chip's on-board oscillator. Pete |
On Sat, 22 Nov 2003 20:03:42 GMT, "Pete KE9OA"
wrote: Has anybody used the oscillator section of the tda1572 with a crystal type of configuration. I looked at the tda1072 application note in one of my old data books, and I don't see how that circuit would even oscillate. I know that it can be done, because the Linn Kudos FM/AM tuner does this with the chip's on-board oscillator. 20-30 years ago TBA120 (Texas SN76660N) was a popular device and used in several numerous applications in Europe, particularly in Germany and Nederland, some of these constructions were published in the "Elektor" magazine (believe the original was Dutch), among the applications I remember: RF mixer phase detector product detector audio mixer oscillators on audio as well as RF syncronous AM detector etc It is no real principal difference between devices like TDA1047, TBA120, NE/SA604, NE614, TDA1576, TBA120, S041P, MC1357P so if you have the schematic of the inner functions, find the phase relation between the limiter input pins and quadrature output connections you should be able to make an xtal oscillator I wrote some note to Radcom (G3VA) about TBA120 applications 20 years ago, but cannot remember today which applications I tested, believe it was found a maximum frequency around 15MHz. The later devices are designed for low-power with low maximum frequency, while the older like Motorola MC1357P (not MC3357) has been used as 70MHz ATV demodulator and was published in such magazine around 1984, one MC1357P was also used as RF limiter. But if your device is a low-poer-type, it might not operate at high enough frequency where you have an xtal to connect. Believe I have some applications on one of my pages, but lack the index, so I'll have to use google to search on my own pages, hi 73 Jan-Martin, LA8AK http://home.online.no/~la8ak/c.htm -- remove ,xnd to reply (Spam precaution!) |
On Sat, 22 Nov 2003 20:03:42 GMT, "Pete KE9OA"
wrote: Has anybody used the oscillator section of the tda1572 with a crystal type of configuration. I looked at the tda1072 application note in one of my old data books, and I don't see how that circuit would even oscillate. I know that it can be done, because the Linn Kudos FM/AM tuner does this with the chip's on-board oscillator. 20-30 years ago TBA120 (Texas SN76660N) was a popular device and used in several numerous applications in Europe, particularly in Germany and Nederland, some of these constructions were published in the "Elektor" magazine (believe the original was Dutch), among the applications I remember: RF mixer phase detector product detector audio mixer oscillators on audio as well as RF syncronous AM detector etc It is no real principal difference between devices like TDA1047, TBA120, NE/SA604, NE614, TDA1576, TBA120, S041P, MC1357P so if you have the schematic of the inner functions, find the phase relation between the limiter input pins and quadrature output connections you should be able to make an xtal oscillator I wrote some note to Radcom (G3VA) about TBA120 applications 20 years ago, but cannot remember today which applications I tested, believe it was found a maximum frequency around 15MHz. The later devices are designed for low-power with low maximum frequency, while the older like Motorola MC1357P (not MC3357) has been used as 70MHz ATV demodulator and was published in such magazine around 1984, one MC1357P was also used as RF limiter. But if your device is a low-poer-type, it might not operate at high enough frequency where you have an xtal to connect. Believe I have some applications on one of my pages, but lack the index, so I'll have to use google to search on my own pages, hi 73 Jan-Martin, LA8AK http://home.online.no/~la8ak/c.htm -- remove ,xnd to reply (Spam precaution!) |
Thanks..............I appreciate the info. I finally found an application
circuit, but using the topology that is described, the circuit behaves more like an LC oscillator vs. a crystal oscillator. This chip must have been designed by a different enginnering team, than the one that did the NE602. The mixer is a real joke, with its 200K output impedance vs. the 1.5K output impedance of the 602. The 602 uses an emitter follower type of oscillator, while the 1072/1572 us a hard to implement differential oscillator. The 602's oscillator is good to 200MHz, while the 1572 is limited to 50MHz. Now I understand why AOR chose to use just the I.F. subsystem/demodulator sections of this chip. I think that I am going to go with a 602 for the 2nd mixer, and use an AGC loop ahead of it. On another note, things are moving ahead at a good rate on the MW receiver design. I've completed the synthesizer, and am now working on optimizing the step response. Reference sidebands are -80dBc, with 2nd, 3rd, and 4th harmonics at -28dBc, -43dBc, and -60dBc respectively. I entered the system of loop filter equations from Motorola's AN1207 appnote into an Excel spreadsheet, eliminating the need to spend a half hour muddling through those equations. I did discover three errors in that appnote, so be careful when using it. The selection of R2's value was shifted over one decimal point, while the value of omegaB was slightly off. The equation for C5's value used an incorrect value for R14. Overall, the real problem with this appnote was one of carelessness; apparently, nobody proofread the document before releasing it for publication. I don't think that I've ever seen so many errors in this type of document, which is why I wonder about the accuracy of that Philips appnote for the 1572. Pete J M Noeding wrote in message ... On Sat, 22 Nov 2003 20:03:42 GMT, "Pete KE9OA" wrote: Has anybody used the oscillator section of the tda1572 with a crystal type of configuration. I looked at the tda1072 application note in one of my old data books, and I don't see how that circuit would even oscillate. I know that it can be done, because the Linn Kudos FM/AM tuner does this with the chip's on-board oscillator. 20-30 years ago TBA120 (Texas SN76660N) was a popular device and used in several numerous applications in Europe, particularly in Germany and Nederland, some of these constructions were published in the "Elektor" magazine (believe the original was Dutch), among the applications I remember: RF mixer phase detector product detector audio mixer oscillators on audio as well as RF syncronous AM detector etc It is no real principal difference between devices like TDA1047, TBA120, NE/SA604, NE614, TDA1576, TBA120, S041P, MC1357P so if you have the schematic of the inner functions, find the phase relation between the limiter input pins and quadrature output connections you should be able to make an xtal oscillator I wrote some note to Radcom (G3VA) about TBA120 applications 20 years ago, but cannot remember today which applications I tested, believe it was found a maximum frequency around 15MHz. The later devices are designed for low-power with low maximum frequency, while the older like Motorola MC1357P (not MC3357) has been used as 70MHz ATV demodulator and was published in such magazine around 1984, one MC1357P was also used as RF limiter. But if your device is a low-poer-type, it might not operate at high enough frequency where you have an xtal to connect. Believe I have some applications on one of my pages, but lack the index, so I'll have to use google to search on my own pages, hi 73 Jan-Martin, LA8AK http://home.online.no/~la8ak/c.htm -- remove ,xnd to reply (Spam precaution!) |
Thanks..............I appreciate the info. I finally found an application
circuit, but using the topology that is described, the circuit behaves more like an LC oscillator vs. a crystal oscillator. This chip must have been designed by a different enginnering team, than the one that did the NE602. The mixer is a real joke, with its 200K output impedance vs. the 1.5K output impedance of the 602. The 602 uses an emitter follower type of oscillator, while the 1072/1572 us a hard to implement differential oscillator. The 602's oscillator is good to 200MHz, while the 1572 is limited to 50MHz. Now I understand why AOR chose to use just the I.F. subsystem/demodulator sections of this chip. I think that I am going to go with a 602 for the 2nd mixer, and use an AGC loop ahead of it. On another note, things are moving ahead at a good rate on the MW receiver design. I've completed the synthesizer, and am now working on optimizing the step response. Reference sidebands are -80dBc, with 2nd, 3rd, and 4th harmonics at -28dBc, -43dBc, and -60dBc respectively. I entered the system of loop filter equations from Motorola's AN1207 appnote into an Excel spreadsheet, eliminating the need to spend a half hour muddling through those equations. I did discover three errors in that appnote, so be careful when using it. The selection of R2's value was shifted over one decimal point, while the value of omegaB was slightly off. The equation for C5's value used an incorrect value for R14. Overall, the real problem with this appnote was one of carelessness; apparently, nobody proofread the document before releasing it for publication. I don't think that I've ever seen so many errors in this type of document, which is why I wonder about the accuracy of that Philips appnote for the 1572. Pete J M Noeding wrote in message ... On Sat, 22 Nov 2003 20:03:42 GMT, "Pete KE9OA" wrote: Has anybody used the oscillator section of the tda1572 with a crystal type of configuration. I looked at the tda1072 application note in one of my old data books, and I don't see how that circuit would even oscillate. I know that it can be done, because the Linn Kudos FM/AM tuner does this with the chip's on-board oscillator. 20-30 years ago TBA120 (Texas SN76660N) was a popular device and used in several numerous applications in Europe, particularly in Germany and Nederland, some of these constructions were published in the "Elektor" magazine (believe the original was Dutch), among the applications I remember: RF mixer phase detector product detector audio mixer oscillators on audio as well as RF syncronous AM detector etc It is no real principal difference between devices like TDA1047, TBA120, NE/SA604, NE614, TDA1576, TBA120, S041P, MC1357P so if you have the schematic of the inner functions, find the phase relation between the limiter input pins and quadrature output connections you should be able to make an xtal oscillator I wrote some note to Radcom (G3VA) about TBA120 applications 20 years ago, but cannot remember today which applications I tested, believe it was found a maximum frequency around 15MHz. The later devices are designed for low-power with low maximum frequency, while the older like Motorola MC1357P (not MC3357) has been used as 70MHz ATV demodulator and was published in such magazine around 1984, one MC1357P was also used as RF limiter. But if your device is a low-poer-type, it might not operate at high enough frequency where you have an xtal to connect. Believe I have some applications on one of my pages, but lack the index, so I'll have to use google to search on my own pages, hi 73 Jan-Martin, LA8AK http://home.online.no/~la8ak/c.htm -- remove ,xnd to reply (Spam precaution!) |
One thing that I forgot to mention............if there is enough interest in
that spreadsheet, I will post it up on my website. Pete J M Noeding wrote in message ... On Sat, 22 Nov 2003 20:03:42 GMT, "Pete KE9OA" wrote: Has anybody used the oscillator section of the tda1572 with a crystal type of configuration. I looked at the tda1072 application note in one of my old data books, and I don't see how that circuit would even oscillate. I know that it can be done, because the Linn Kudos FM/AM tuner does this with the chip's on-board oscillator. 20-30 years ago TBA120 (Texas SN76660N) was a popular device and used in several numerous applications in Europe, particularly in Germany and Nederland, some of these constructions were published in the "Elektor" magazine (believe the original was Dutch), among the applications I remember: RF mixer phase detector product detector audio mixer oscillators on audio as well as RF syncronous AM detector etc It is no real principal difference between devices like TDA1047, TBA120, NE/SA604, NE614, TDA1576, TBA120, S041P, MC1357P so if you have the schematic of the inner functions, find the phase relation between the limiter input pins and quadrature output connections you should be able to make an xtal oscillator I wrote some note to Radcom (G3VA) about TBA120 applications 20 years ago, but cannot remember today which applications I tested, believe it was found a maximum frequency around 15MHz. The later devices are designed for low-power with low maximum frequency, while the older like Motorola MC1357P (not MC3357) has been used as 70MHz ATV demodulator and was published in such magazine around 1984, one MC1357P was also used as RF limiter. But if your device is a low-poer-type, it might not operate at high enough frequency where you have an xtal to connect. Believe I have some applications on one of my pages, but lack the index, so I'll have to use google to search on my own pages, hi 73 Jan-Martin, LA8AK http://home.online.no/~la8ak/c.htm -- remove ,xnd to reply (Spam precaution!) |
One thing that I forgot to mention............if there is enough interest in
that spreadsheet, I will post it up on my website. Pete J M Noeding wrote in message ... On Sat, 22 Nov 2003 20:03:42 GMT, "Pete KE9OA" wrote: Has anybody used the oscillator section of the tda1572 with a crystal type of configuration. I looked at the tda1072 application note in one of my old data books, and I don't see how that circuit would even oscillate. I know that it can be done, because the Linn Kudos FM/AM tuner does this with the chip's on-board oscillator. 20-30 years ago TBA120 (Texas SN76660N) was a popular device and used in several numerous applications in Europe, particularly in Germany and Nederland, some of these constructions were published in the "Elektor" magazine (believe the original was Dutch), among the applications I remember: RF mixer phase detector product detector audio mixer oscillators on audio as well as RF syncronous AM detector etc It is no real principal difference between devices like TDA1047, TBA120, NE/SA604, NE614, TDA1576, TBA120, S041P, MC1357P so if you have the schematic of the inner functions, find the phase relation between the limiter input pins and quadrature output connections you should be able to make an xtal oscillator I wrote some note to Radcom (G3VA) about TBA120 applications 20 years ago, but cannot remember today which applications I tested, believe it was found a maximum frequency around 15MHz. The later devices are designed for low-power with low maximum frequency, while the older like Motorola MC1357P (not MC3357) has been used as 70MHz ATV demodulator and was published in such magazine around 1984, one MC1357P was also used as RF limiter. But if your device is a low-poer-type, it might not operate at high enough frequency where you have an xtal to connect. Believe I have some applications on one of my pages, but lack the index, so I'll have to use google to search on my own pages, hi 73 Jan-Martin, LA8AK http://home.online.no/~la8ak/c.htm -- remove ,xnd to reply (Spam precaution!) |
I discovered that you can inject a signal into pin 14 of this chip, removing
the necessity for fiddling with the internal oscillator. The internal oscillator is great for LC circuits............you merely place the tuned circuit between pins 13 and 14, and it flies! You just have to set the injection level so that the buffered signal at pin 12 is right around 320mV p-p. Pete Pete KE9OA wrote in message ... One thing that I forgot to mention............if there is enough interest in that spreadsheet, I will post it up on my website. Pete J M Noeding wrote in message ... On Sat, 22 Nov 2003 20:03:42 GMT, "Pete KE9OA" wrote: Has anybody used the oscillator section of the tda1572 with a crystal type of configuration. I looked at the tda1072 application note in one of my old data books, and I don't see how that circuit would even oscillate. I know that it can be done, because the Linn Kudos FM/AM tuner does this with the chip's on-board oscillator. 20-30 years ago TBA120 (Texas SN76660N) was a popular device and used in several numerous applications in Europe, particularly in Germany and Nederland, some of these constructions were published in the "Elektor" magazine (believe the original was Dutch), among the applications I remember: RF mixer phase detector product detector audio mixer oscillators on audio as well as RF syncronous AM detector etc It is no real principal difference between devices like TDA1047, TBA120, NE/SA604, NE614, TDA1576, TBA120, S041P, MC1357P so if you have the schematic of the inner functions, find the phase relation between the limiter input pins and quadrature output connections you should be able to make an xtal oscillator I wrote some note to Radcom (G3VA) about TBA120 applications 20 years ago, but cannot remember today which applications I tested, believe it was found a maximum frequency around 15MHz. The later devices are designed for low-power with low maximum frequency, while the older like Motorola MC1357P (not MC3357) has been used as 70MHz ATV demodulator and was published in such magazine around 1984, one MC1357P was also used as RF limiter. But if your device is a low-poer-type, it might not operate at high enough frequency where you have an xtal to connect. Believe I have some applications on one of my pages, but lack the index, so I'll have to use google to search on my own pages, hi 73 Jan-Martin, LA8AK http://home.online.no/~la8ak/c.htm -- remove ,xnd to reply (Spam precaution!) |
I discovered that you can inject a signal into pin 14 of this chip, removing
the necessity for fiddling with the internal oscillator. The internal oscillator is great for LC circuits............you merely place the tuned circuit between pins 13 and 14, and it flies! You just have to set the injection level so that the buffered signal at pin 12 is right around 320mV p-p. Pete Pete KE9OA wrote in message ... One thing that I forgot to mention............if there is enough interest in that spreadsheet, I will post it up on my website. Pete J M Noeding wrote in message ... On Sat, 22 Nov 2003 20:03:42 GMT, "Pete KE9OA" wrote: Has anybody used the oscillator section of the tda1572 with a crystal type of configuration. I looked at the tda1072 application note in one of my old data books, and I don't see how that circuit would even oscillate. I know that it can be done, because the Linn Kudos FM/AM tuner does this with the chip's on-board oscillator. 20-30 years ago TBA120 (Texas SN76660N) was a popular device and used in several numerous applications in Europe, particularly in Germany and Nederland, some of these constructions were published in the "Elektor" magazine (believe the original was Dutch), among the applications I remember: RF mixer phase detector product detector audio mixer oscillators on audio as well as RF syncronous AM detector etc It is no real principal difference between devices like TDA1047, TBA120, NE/SA604, NE614, TDA1576, TBA120, S041P, MC1357P so if you have the schematic of the inner functions, find the phase relation between the limiter input pins and quadrature output connections you should be able to make an xtal oscillator I wrote some note to Radcom (G3VA) about TBA120 applications 20 years ago, but cannot remember today which applications I tested, believe it was found a maximum frequency around 15MHz. The later devices are designed for low-power with low maximum frequency, while the older like Motorola MC1357P (not MC3357) has been used as 70MHz ATV demodulator and was published in such magazine around 1984, one MC1357P was also used as RF limiter. But if your device is a low-poer-type, it might not operate at high enough frequency where you have an xtal to connect. Believe I have some applications on one of my pages, but lack the index, so I'll have to use google to search on my own pages, hi 73 Jan-Martin, LA8AK http://home.online.no/~la8ak/c.htm -- remove ,xnd to reply (Spam precaution!) |
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