Parviz Ghaffaripour - Saratoga CA Sai L. Ting - San Jose CA
Assignee:
National Semiconductor Corporation - Santa Clara CA
International Classification:
H03F 114
US Classification:
330 51
Abstract:
An amplifier circuit with improved turn-on and turn-off transient operation includes an amplifier and a controller for controlling the mode of operation of the amplifier during initial and subsequent circuit turn-on and turn-off. The amplifier is biased by a positive power supply voltage and has a differential input which is driven by a reference voltage and a single-ended input signal. Where the output is single-ended, a single amplifier provides a single-ended output signal. Where the output is differential, the amplifier includes cascaded, differential input, single-ended output amplifiers which together provide a differential output signal. One of each of the differential inputs is driven by the reference voltage which, following circuit turn-on, charges to a value of half of the positive power supply voltage. Following circuit turn on and turn-off and during initial charging or discharging, respectively, of the reference voltage, the controller places the amplifier in an operation mode whereby the single-ended output signal follows the relatively slowly charging or discharging reference voltage and the differential output signal remains at zero. When the reference voltage is fully charged, the controller places the amplifier in another operation mode whereby both the single-ended and differential output signals become equal to the sum of the reference voltage and a multiple of the input signal.
Amplifier Circuit With Reduced Dc Power Related Transients
Parviz Ghaffaripour - Saratoga CA Arthur J. Kalb - San Jose CA Nick M. Johnson - Los Altos CA Sai L. Ting - San Jose CA
Assignee:
National Semiconductor Corporation - Santa Clara CA
International Classification:
H03F 126
US Classification:
330 51
Abstract:
An amplifier circuit with improved turn-on transient operation includes a differential amplifier and a selectively variable reference generator for controlling the amplifier output during circuit turn-on. The amplifier is biased by a single power supply and its differential inputs are driven by a reference voltage from the reference generator and a single-ended input signal. Following circuit turn-on, the selectively variable reference voltage, generated by charging the bypass capacitor with a constant current source, charges in a linear manner from ground potential toward its final value of, typically, half of the power supply voltage. This allows improved turn-on transient operation to be realized, e. g. reduced "pops" and "clicks" upon circuit turn-on, while giving the user increased flexibility in selecting the sizes of the reference voltage bypass capacitor and the input signal coupling capacitor.
A bias control circuit and an associated method in an audio output amplifier provide slow turn-on or turn-off operation of a bias voltage generation circuit, using an external bypass capacitor. A slow rate in the turn-on and turn-off operations in such a bias voltage generation circuit prevents click or pop noises. In one embodiment, two bipolar transistors each responsive to the voltage on an external capacitor are provided to gradually increase the voltage of an output node, which can be used to drive the gate terminal of an MOS transistor in the bias voltage generation circuit. Alternatively, in another embodiment, an MOS inverter, which receives as input the voltage on bypass capacitor, is provided to divert current from a conventional bias circuit. The rate at which the MOS inverter diverts current from the conventional bias circuit controls the slew rate in the turn-off operation of the bias current. Adjustment to this slew rate can be accomplished by adjusting the resistance and capacitance values of resistor and bypass capacitor, respectively.
Amplifier Circuit With Reduced Turn-On And Turn-Off Transients
Parviz Ghaffaripour - Saratoga CA Nick M. Johnson - Los Altos CA
Assignee:
National Semiconductor Corporation - Santa Clara CA
International Classification:
H03F 126
US Classification:
330 51
Abstract:
An amplifier circuit with improved turn-on and turn-off transient operation includes an amplifier and a controller for controlling the amplifier output during initial and subsequent circuit turn-on and turn-off. The amplifier is biased by a positive power supply voltage and has a differential input driven by a reference voltage and a single-ended input signal. Where the output is single-ended, a single amplifier provides a single-ended output signal. Where the output is differential, the amplifier includes cascaded, differential input, single-ended output amplifiers which together provide a differential output signal. Following circuit turn-on and turn-off, the reference voltage, which drives one of each of the differential inputs, typically charges to or discharges from, respectively, a value of half of the positive power supply voltage. Following circuit turn-on and turn-off and during initial charging or discharging, respectively, of the reference voltage, the controller forces the single-ended output signal to follow the relatively slowly charging or discharging reference voltage and the differential output signal to remain at zero. When the reference voltage is fully charged, the controller releases control and both the single-ended and differential output signals become equal to the sum of the reference voltage and a multiple of the input signal.
6399 San Ignacio Ave STE 250, San Jose, CA 95119 6399 San Ignacio Ave Sute 250, San Jose, CA 95119 262 Santa Ana Ct, Sunnyvale, CA 94085 275 Turn Pike Dr, Folsom, CA 95630 916-351-8100
Parviz Ghaffaripour President
Aspired Integrated Circuits Corporation
14510 Big Basin Way, Saratoga, CA 95070
Parviz Ghaffaripour Executive Vice-President
Skyworks Solutions, Inc Manufacturer of Power Management Semiconductor Products · Mfg Power Mgmt Semiconductor Products · Mfg Semiconductors/Related Devices
3230 Scott Blvd, Santa Clara, CA 95054 120 Stony Pt Rd, Santa Rosa, CA 95401 408-737-4600, 707-535-3507
Exar Corporation - Fremont, CA since May 2013
Sr. Vice President
Akros Silicon - Sunnyvale, CA Sep 2008 - Apr 2013
President & CEO, Board Director, Adviser
Analogic Tech Feb 2007 - Jun 2008
COO & EVP
Aspired IC 2006 - Feb 2007
CEO
Maxim Integrated Products 1999 - 2006
VP
Education:
Santa Clara University 1985 - 1988
University of California, Berkeley 1980 - 1983
Youtube
Exar explains their latest programmable power...
In this video Parviz Ghaffaripour, SVP & GM of Exar, explains their la...