Switching regulator with asymmetrical feedback amplifier and method

• US 5,220,272 A
• Filed: 09/10/1990
• Issued: 06/15/1993
• Est. Priority Date: 09/10/1990
• Status: Expired due to Term

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Linear Technology Corporation (Analog Devices, Inc.)
• Inventors: Nelson, Carl T.
• Primary Examiner(s): Stephan, Steven L.
• Assistant Examiner(s): VOELTZ, EMANUEL T
• Application Number:
  US07/579,773
• Time in Patent Office: 1,009 Days
• Field of Search: 363/17, 363/49, 323/282, 323/284, 323/288, 323/273, 323/274, 323/280, 323/351, 323/352, 323/353, 330/252, 330/257
• US Class Current: 323/282
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H03F 2203/45656 the LC comprising one diode of a current mirror, i.e. forming an asymmetrical load
• CPC Class Codes: H03F 2203/45658 the LC comprising two diodes of current mirrors
• CPC Class Codes: H03F 2203/45664 the LC comprising one or more cascaded inverter stages as output stage at one output of the dif amp circuit
• CPC Class Codes: H03F 2203/45674 the LC comprising one current mirror
• CPC Class Codes: H03F 2203/45696 the LC comprising more than two resistors
• CPC Class Codes: H03F 2203/45721 the LC comprising only an output circuit for one phase of the signal
• CPC Class Codes: H03F 3/45071 with semiconductor devices only
• CPC Class Codes: H03F 3/45085 Long tailed pairs H03F3/45112, H03F3/45139 take precedence

Abstract

A switching regulator network is disclosed which receives an input voltage and provides a regulated constant output supply voltage. The regulator includes a pulse width modulated switching circuit which regulates the output voltage responsive to a feedback error signal. A transconductance error amplifier produces an error feedback signal which is proportional to the difference between the reference input voltage and the output voltage. The overshoot of the output supply voltage is minimized by including a means in the transconductance error amplifier to provide a higher negative slew rate current than the positive slew rate current. This is done without employing extra pins or parts in the integrated circuit.

Claims

1. A switching regulator network for receiving input voltage and providing a regulator output voltage including:

a pulse width modulated switching circuit which regulates the output voltage responsive to a feedback error signal,

a transconductance error amplifier for sampling the output voltage and comparing it to a reference voltage and providing said feedback error signal whereby to regulate the output voltage, said transconductance amplifier including means for providing a higher negative rate of change of feedback error signal than positive rate of change of feedback error signal.

2. A switching regulator as in claim 1 including an impedance network across which said feedback error signal is developed and in which said transconductance amplifier supplies a different maximum current to charge said impedance network than to discharge said network to provide different slew rates.

3. A switching regulator as in claim 2 in which said transconductance amplifier includes a pair of input transistors having emitter, base, and collector connected with their emitters in common to constant current source, with their bases connected to compare the output voltage to said reference voltage, and with their collectors coupled to regulate the output voltage, said transistors having their emitter areas selected so that the current density through the transistors from said current source is equal under quiescent operation with the output voltage in regulation.