Amplifier assembly including variable gain amplifier, parallel programmable amplifiers, and AGC
View Patent ↗An amplifier assembly receives an input signal including multiple frequency channels. A first stage amplifier amplifies the input signal, to produce at an output thereof an amplified first signal including the multiple frequency channels. A plurality of second stage amplifiers have their respective inputs coupled to an output of the first stage amplifier. Each second stage amplifier amplifies the amplified first signal, to produce at its respective output a respective second amplified signal including the multiple frequency channels. The first stage amplifier and the second stage amplifiers are variable gain amplifiers, and are constructed on a common Integrated Circuit (IC) substrate.
1. An amplifier assembly, comprising:
a first stage amplifier configured to amplify an input signal, to thereby produce at an output of the first stage amplifier an amplified first signal having multiple frequency channels;
a plurality of second stage amplifiers having their respective inputs coupled to an output of the first stage amplifier, each second stage amplifier being configured to amplify the amplified first signal, to thereby produce at its respective output a respective second amplified signal including the multiple frequency channels;
an integrated circuit (IC) substrate, wherein the first stage amplifier and the plurality of second stage amplifiers are constructed on the IC substrate; and
a process sense circuit constructed on the IC substrate for producing a sensed signal indicative of a process-based parameter of the IC substrate, wherein the process-based parameter is one or more of:
a transconductance of the IC substrate;
a resistivity per unit area of the IC substrate; and
a threshold voltage for transistors constructed on the IC substrate.
2. The amplifier assembly of claim 1 , wherein the first stage amplifier is a first stage Variable Gain Amplifier (VGA) configured to have a gain controlled in response to one or more gain control signals.
3. The amplifier assembly of claim 1 , further comprising:
an Automatic Gain Control (AGC) module configured to generate the one or more gain control signals responsive to a power of the first amplified signal.
4. The amplifier assembly of claim 3 , wherein the first stage VGA includes a plurality of variable gain stages arranged in parallel with one another, each of the gain stages having a gain controlled responsive to a corresponding one of the one or more gain control signals.
5. The amplifier assembly of claim 3 , wherein the AGC module is configured to generate the one or more AGC control signals according to a ramp function, and thereby change the gain of the first stage VGA according to the ramp function.
6. The amplifier assembly of claim 5 , wherein the gain change of the first stage VGA is smooth and continuous responsive to the ramp function.
7. The amplifier assembly of claim 3 , wherein an input of the AGC module is coupled to an output of one of the second stage amplifiers.
8. The amplifier assembly of claim 1 , wherein each second stage amplifier is a second stage VGA.
9. An amplifier assembly, comprising:
a first stage amplifier configured to amplify an input signal, to thereby produce at an output of the first stage amplifier an amplified first signal having multiple frequency channels;
a plurality of second stage amplifiers having their respective inputs coupled to an output of the first stage amplifier, each second stage amplifier being configured to amplify the amplified first signal, to thereby produce at its respective output a respective second amplified signal including the multiple frequency channels, wherein each second stage amplifier is a second stage VGA, each of a first sub-plurality of the second stage Variable Gain Amplifiers (VGAs) has a first gain, and each of a second sub-plurality of the second stage VGAs has a second gain that is less than the first gain;
an integrated circuit (IC) substrate, wherein the first stage amplifier and the plurality of second stage amplifiers are constructed on the IC substrate; and
a process sense circuit constructed on the IC substrate for producing a sensed signal indicative of a process-based parameter of the IC substrate, wherein a gain of one or more of the plurality of second stage amplifiers is based on an output of the process sense circuit.
10. The amplifier assembly of claim 9 , wherein a ratio of the first gain to the second gain is in a range of ratios of 1:1 to 2:1.
11. The amplifier assembly of claim 1 , wherein the input signal is a TV signal including multiple TV channels.
12. The amplifier assembly of claim 1 , wherein the input signal is at least one of an NTSC TV signal, a PAL TV signal, a SECAM TV signal, a digital data signal, and a digital TV signal.
13. The amplifier assembly of claim 1 , wherein the first stage amplifier is a differential amplifier.
14. The amplifier assembly of claim 1 , wherein each of the second stage amplifiers is a differential amplifier.
15. The amplifier assembly of claim 1 , wherein the first stage amplifier includes a plurality of gain stages arranged in parallel with each other, and having their respective outputs combined together at the first stage amplifier output.
16. The amplifier assembly of claim 1 , wherein the first stage amplifier includes:
an input node;
a first plurality of amplifiers having their inputs coupled to the input node;
an attenuation ladder coupled to the input node; and
a second plurality of amplifiers having their respective inputs coupled to successive corresponding taps of the attenuation ladder, wherein the outputs of the first plurality of amplifiers and the outputs of the second plurality of amplifiers are combined together at the output of the first stage amplifier.
17. The amplifier assembly of claim 16 , further comprising:
an integrated circuit (IC) substrate, the first stage amplifier being constructed on the IC substrate; and
an input resistor external to the IC substrate and coupled to the input node, wherein the input resistor and the attenuation ladder together set an input impedance of the amplifier assembly.
18. The amplifier assembly of claim 1 , further comprising:
a control interface coupled to the first stage amplifier and each of the second stage amplifiers, the control interface being configured to perform at least one of the following:
set the gain of the first stage amplifier;
access the gain of the first stage amplifier; and
set the gain of each of the second stage amplifiers.
19. An amplifier assembly, comprising:
an IC substrate;
a first stage Variable Gain Amplifier (VGA) configured to have a gain controlled in response to one or more gain control signals;
a plurality of parallel second stage Variable Gain Amplifiers (VGAs) having their respective inputs coupled to an output of the VGA;
an AGC module configured to generate the one or more control signals responsive to a power of an amplified signal produced by the first stage VGA;
a control interface coupled to the first stage VGA, each of the second stage VGAs, and the AGC module; and
wherein the first stage VGA, each of the second stage VGAs, and the control interface, and at least a portion of the AGC module are all constructed on the IC substrate; and
a process monitor, constructed on the IC substrate, for monitoring process-based parameters of the IC substrate, wherein the process-based parameter is one or more of:
a transconductance of the IC substrate;
a resistivity per unit area of the IC substrate; and
a threshold voltage for transistors constructed on the IC substrate.
20. The amplifier assembly of claim 19 , wherein the control interface is coupled to the processor monitor.
21. The amplifier assembly of claim 1 , wherein the sensed signal indicative of the process-based parameter of said IC substrate may adjust a gain in one or more of:
the first stage amplifier; and
at least one amplifier in the plurality of second stage amplifiers.
22. The amplifier assembly of claim 19 , wherein the sensed signal indicative of the process-based parameter of the IC substrate may adjust a gain in one or more of:
the first stage VGA; and
at least one amplifier in said plurality of parallel second stage VGAs.
23. The amplifier assembly of claim 1 , wherein a gain of one or more of the plurality of second stage amplifiers is based on the sensed signal.
24. The amplifier assembly of claim 19 , wherein a gain of one or more of the parallel second stage VGAs is based on an output of the process monitor.