Amplifier having digital bias control apparatus

• US 4,924,191 A
• Filed: 04/18/1989
• Issued: 05/08/1990
• Est. Priority Date: 04/18/1989
• Status: Expired due to Term

• Current Assignee: MKS Instruments Incorporated
• Original Assignee: Erbtec Engineering, Inc. (Roper Technologies, Inc.)
• Inventors: Bandhauer, Brian D., Erb, Lee A., Beaty, Paul G., Carr, Alan R., Randall, Mitchell A.
• Primary Examiner(s): Mullins, James B.
• Application Number:
  US07/340,385
• Time in Patent Office: 385 Days
• Field of Search: 330/2, 330/123, 330/124 R, 330/129, 330/130, 330/134, 330/267, 330/273, 330/289, 330/295, 330/296
• US Class Current: 330/130
• CPC Class Codes: H03F 1/0244 Stepped control

Abstract

This amplifier is equipped with a digital bias control apparatus to provide precise, dynamic control over the operating point of a plurality of amplifying elements in the ampliifer. A processor optimizes the operating point of each individual amplifying element as a function of the amplifying element characteristics, the operating environment and the applied input signal. The use of a processor also enables the user to remotely program the operating point of each individual amplifying element in the amplifier. The processor further enables dynamic changes in the operating characteristics of the amplifier as the operating environment of these amplifing elements changes. The processor also generates an alarm signal if any particular amplifying element is operating out of its nominal specifications. This digital bias control apparatus can function in class A, AB, B or C type of amplifiers whether they are tuned or untuned and whether the amplifier operates in a pulsed or continuous mode.

Claims

1. In an amplifier circuit having a plurality of active amplifying elements, a digital control method for regulating the operating point of at least one of said active amplifying elements comprising the steps of:

storing, in a memory, bias signal values individual to each of said active amplifying elements;

placing a selected one of said active amplifying elements in an active, no input signal condition;

reading from said memory a bias signal value individual to said selected active amplifying element;

applying a bias signal representative of said bias signal value to said selected active amplifying element;

monitoring the output current of said selected active amplifying element;

adjusting said bias signal value if said monitored output current varies from a predetermined value by greater than a predetermined amount.

2. The method of claim 1 wherein said step of applying includes the step of:

converting said bias signal value read from said memory into an analog bias signal representative of said bias signal value.

3. The method of claim 1 wherein said amplifier operates in a pulsed mode, said step of placing includes the step of:

blanking all of said amplifying elements less said selected amplifying element during the intra-input signal pulse time.

4. The method of claim 1 wherein at least one of said amplifying elements are field effect transistors, said step of applying includes the step of:

applying a bias voltage to the gate terminal of said selected one of said field effect transistor amplifying elements.

5. The method of claim 1 wherein at least one of said amplifying elements are vacuum tubes, said step of applying includes the step of:

applying a bias voltage to the control terminal of said selected one of said vacuum tube amplifying elements.

6. The method of claim 1 wherein said step of adjusting includes the steps of:

modifying said bias signal value associated with said selected amplifying element;

writing said modified bias signal value into said memory in place of said bias signal value read from said memory by said reading means.

7. The method of claim 1 further including the step of:

interconnecting said control apparatus with a data link;

writing, in response to data signals received via said data link indicative of modified bias signal values, said modified bias signal values into said memory in place of the bias signal values stored therein.

8. The method of claim 1 further comprising the step of:

sequentially selecting each of said amplifying elements in said amplifier.

9. In an amplifier circuit that includes a plurality of amplifying elements, a digital control apparatus for regulating the operating point of said amplifying elements comprising:

means for storing bias signal values individual to each of said amplifying elements;

means for selecting an individual one of said amplifying elements for operating point testing;

means for applying a bias signal representative of the associated one of said stored bias signal values to said selected amplifying element;

means for monitoring the output signal generated by said selected amplifying element;

means responsive to said monitored output signal for modifying said associated stored bias signal value if said monitored output signal deviated from a predetermined value by greater than a predetermined amount.

10. The apparatus of claim 9 wherein said apparatus further includes:

means for enabling remote access by a user to said storing means to modify said stored bias signal values.

11. The apparatus of claim 9 further including:

means for monitoring at least one environmental parameter in said amplifier;

means for monitoring at least one operational parameter in said amplifier;

wherein said modifying means is responsive to said monitored operational parameters for adjusting said stored bias signal value if said monitored parameters vary by greater than a predetermined amount from a nominal value.