Charge pump amplifier

• US 4,425,550 A
• Filed: 12/24/1981
• Issued: 01/10/1984
• Est. Priority Date: 12/24/1981
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Smith, Michael D., Miller, James A.
• Primary Examiner(s): Mullins, James B.
• Assistant Examiner(s): Wan, Gene
• Application Number:
  US06/334,280
• Time in Patent Office: 747 Days
• Field of Search: 330/107, 330/302, 330/109, 330/151, 330/278
• US Class Current: 330/107
• CPC Class Codes: H03F 3/005 using switched capacitors, e.g. dynamic amplifiers; using switched capacitors as resistors in differential amplifiers H03F3/45 takes precedence

Abstract

A charge pump amplifier useful for providing precise gain in integrated circuits is described. The amplifier uses an operational amplifier with a capacitive feedback to accumulate successive charges applied to the input of the operational amplifier by a switched-capacitor input. If the capacitors are of equal size, the gain of the amplifier is a function of the ratio of the frequency of the switched capacitor input and the frequency of discharge of the feedback capacitor.

Claims

1. A charge pump amplifier comprising:

an operational amplifier having an input and an output;

feedback means connected between the input and the output of the operational amplifier and comprising a storage means;

means selectively coupled to the input of the operational amplifier and to a voltage source, for storing a charge from the voltage source, and for transferring the stored charge to the input of the operational amplifier;

means for selectively discharging the storage means at a rate different than the rate at which the stored charges are applied to input of the operational amplifier;

whereby a plurality of charges from the means for storing a charge are transferred to the storage means, and the plurality of the charges are accumulated by the storage means prior to the discharge thereof.

2. A charge pump amplifier as set forth in claim 1 wherein the means for storing a charge and for transferring the stored charge comprises a capacitor coupled to a switch.

3. A charge pump amplifier as set forth in claims 1 or 2 wherein the feedback means comprises a feedback capacitor.

4. A charge pump amplifier as set forth in claim 3 further comprising a switch, the switch being coupled in parallel to the feedback capacitor, and selectively operable to discharge the feedback capacitor.

5. A charge pump amplifier as set forth in claim 4 wherein the capacitor and the feedback capacitor are of equal size, whereby the voltage at the output of the operational amplifier is a function of the voltage at the voltage source and the number of charges transferred to the feedback capacitor before the feedback capacitor is selectively discharged.