Circuits and methods for compensating switched mode amplifiers
First Claim
1. An amplifier system comprising:
- switching amplifier circuitry for driving a load;
analog conversion circuitry for recovering an analog signal from an output signal of said switching amplifier circuitry;
an adaptive filter coupled to an output of said analog conversion circuitry, for deriving an inverse transfer function through said amplifier system and generating a coefficient map in response; and
a compensation filter coupled to said switching amplifier circuitry and responsive to said coefficient map for compensating for variations in said load.
1 Assignment
0 Petitions
Accused Products
Abstract
A system and method for compensating switched mode amplifiers. The amplifier system includes an adaptive filter coupled to the output of circuitry that recovers the analog signal from the output of the switching amplifier circuitry. The adaptive filter derives an inverse transfer function of the forward path through the system. The derived inverse transfer function is used to generate a coefficient map which a compensation filter responsively compensates for from variations in the output load of the amplifier system. In the disclosed method, the deriving the inverse transfer function may further include calibrating the adaptive filter continuously, at system startup or in response to user demand.
-
Citations
26 Claims
-
1. An amplifier system comprising:
-
switching amplifier circuitry for driving a load;
analog conversion circuitry for recovering an analog signal from an output signal of said switching amplifier circuitry;
an adaptive filter coupled to an output of said analog conversion circuitry, for deriving an inverse transfer function through said amplifier system and generating a coefficient map in response; and
a compensation filter coupled to said switching amplifier circuitry and responsive to said coefficient map for compensating for variations in said load. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
control circuitry for receiving an input signal to be amplified; and
a switching unit configured to output an amplified signal in response to a drive signal from said control circuitry.
-
-
3. The system of claim 2 wherein said control circuitry comprises a pulse width modulator (PWM).
-
4. The system of claim 1 wherein said forward path comprises said amplifier unit, said analog conversion circuitry and a load for receiving said analog signal coupled to said analog conversion circuitry.
-
5. The system of claim 1 wherein said analog conversion circuitry comprises a low pass filter (LPF).
-
6. The system of claim 1 further comprising a compensation filter coupled to an input of said amplifier unit, said compensation filter configured to generate said an inverse transfer function in response to data from said adaptive filter.
-
7. The system of claim 6 wherein said adaptive filter comprises a first finite impulse response digital filter (FIR) and said data comprises coefficient values of said first FIR.
-
8. The system of claim 7 further comprising an analog to digital converter (ADC) coupled between an output of said analog conversion circuitry and said adaptive filter.
-
9. The system of claim 1 further comprising a noise source, said noise source operable for providing an input signal to said switching amplifier circuitry, in response to an adaptation cycle for training said adaptive filter.
-
10. The system of claim 1 further comprising adder circuitry configured to receive a signal input to said amplifier unit and an output signal from said adaptive filter, said adaptive filter deriving said inverse transfer function in response to an error signal from said adder circuitry, said error signal comprising a difference of said signal input to said amplifier unit and said output signal from said adaptive filter.
-
11. The system of claim 7 wherein said compensation filter comprises a second finite impulse response digital filter (FIR), and wherein said second FIR is configured in response to copying said coefficient values of said first FIR to said second FIR.
-
12. The amplifier systems of claim 1, wherein the switching amplifier drives the load through an output filter of a selected frequency response.
-
13. A method of compensating for load variations in a switching amplifier system comprising the steps of:
-
deriving an inverse transfer function through the amplifier system using an adaptive filter;
generating a coefficient map corresponding to the inverse transfer function; and
applying the coefficient map to a compensation filter in the forward path of the amplifier system to compensate for variations in the load. - View Dependent Claims (14, 15, 16, 17, 18, 19)
-
-
20. An amplifier comprising:
-
switched- mode amplifier circuitry for amplifying an input signal;
circuitry for recovering an audio signal from an output signal from said amplifier means; and
circuitry for deriving an inverse transfer function of a forward path through said amplifier. - View Dependent Claims (21, 22, 23, 24, 25, 26)
-
Specification