Gain control methods and systems in an amplifier assembly
View Patent ↗A Variable Gain Amplifier (VGA) amplifies an input signal according to a gain, to produce an amplified signal. A detector module detects a power indicative of a power of the amplified signal. A comparator module compares the detected power to a high threshold, a low threshold and a target threshold intermediate the high and low thresholds. A controller module changes the gain of the VGA so as to drive the detected power in a direction toward the middle threshold when the comparator module indicates the detected power is not between the high and low thresholds.
1. A method of amplification, comprising:
(a) amplifying an input signal using one or more activated gain stages of a plurality of parallel gain stages to produce a first output signal, a gain of the amplification being a sum of respective fixed gains of the one or more activated gain stages of the plurality of gain stages;
(b) providing the first output signal to N individually programmable amplifier(s) to produce N second output signal(s), respectively, wherein N is a natural number; and
(c) detecting a power of one or more of the N second output signals, and changing the gain of the amplification so as to drive the power between a high threshold and a low threshold when the power is not between the high and low thresholds.
2. The method of claim 1 , wherein step (c) comprises changing the gain of the amplification until the power crosses a target threshold, wherein the target threshold is between the high and low thresholds.
3. The method of claim 1 , further comprising not changing the gain of the amplification when the power is between the high and low thresholds.
4. The method of claim 1 , further comprising repeating step (c) at predetermined time intervals.
5. The method of claim 1 , wherein step (c) comprises changing the gain of the amplification according to a ramp function.
6. The method of claim 1 , wherein step (c) comprises:
decreasing the gain of the amplification when the power is above the high threshold; and
increasing the gain of the amplification when the power is below the low threshold.
7. An amplification apparatus, comprising:
a plurality of parallel gain stages to amplify an input signal and having a combined gain that is a sum of respective fixed gains of one or more activated gain stages of the plurality of gain stages, so as to produce a first amplified output signal;
N individually programmable amplifier(s) to produce N second amplified output signal(s), respectively, from the first output signal, wherein N is a natural number;
a detector module to detect a power of one or more of the N second amplified output signals; and
a controller module to change the combined gain, so as to drive the power between a high threshold and a low threshold.
8. The apparatus of claim 7 , further comprising:
a comparator module to compare the power of the amplified signal to the high and low thresholds.
9. The apparatus of claim 8 , wherein the controller module:
decreases the combined gain when the comparator module indicates the power is above the high threshold; and
increases the combined gain when the comparator module indicates the power is below the low threshold.
10. The apparatus of claim 8 , wherein the controller module does not change the combined gain when the comparator module indicates the power is between the high and low thresholds.
11. The apparatus of claim 7 , wherein at least some of the parallel gain stages are non-attenuated gain stages having substantially equal maximum gains.
12. The apparatus of claim 7 , wherein at least some of the parallel gain stages are attenuated gain stages having progressively decreasing maximum gain.
13. The apparatus of claim 12 , wherein the individual attenuated gain stages further comprise:
an amplifier; and
an attenuator, wherein the individual attenuated gain stages are cascaded in parallel such that the individual attenuated gain stages share attenuators.
14. The apparatus of claim 13 , wherein the attenuators of the individual attenuated gain stages have a fixed attenuation.
15. The apparatus of claim 13 , wherein the attenuators of the individual attenuated gain stages have a programmable attenuation.
16. The apparatus of claim 12 , further comprising a resistor ladder, wherein the individual attenuated gain stages are coupled to successive taps of the resistor ladder.
17. The apparatus of claim 12 , wherein each individual attenuated gain stage further comprises an amplifier, wherein the amplifiers of the individual attenuated gain stages have progressively decreasing size.
18. The apparatus of claim 7 , wherein at least some of the parallel gain stages are fixed-attenuated gain stages having substantially equal constant attenuation.
19. The apparatus of claim 18 , wherein each individual fixed-attenuated gain stages further comprises an amplifier, wherein the individual fixed-attenuated gain stages share a single attenuator.