Preamplifier circuit
AssigneeHoneywell Inc.
InventorTed B. Gilbert
Life of this patent
Estimating the term…
Abstract
A preamplifier for a magnetic record reproducing system includes a differential amplifier construction wherein the input stage may be configured as a differential cascode arrangement for minimum noise at the lower frequency range or to be configured as an emitter-follower for maximum input impedance at the upper frequency range. The structure allows the amplifier to respond to very high frequencies, on the order of 4 MHz, without the introduction of an undesirable phase shift in the reproduced signal.
Claims10
In a magnetic record system wherein means are provided for selectively driving the record member at any of a number of different speeds, and having a playback transducer, a wide frequency band preamplifier, said preamplifier comprising:
- a first stage differential amplifier having input terminals connected to said transducer, said first stage amplifier being selectively configured in either of two operational modes;
- in a first said operational mode, said first stage amplifier being configured in a differential cascode amplifier;
- an output stage differential amplifier, said first stage differential cascode amplifier, in said first operational mode having an output connected as differential input to said output stage differential amplifier,
- in a second said operational mode, said first stage amplifier being configured as a differential emitter-follower amplifier;
- and
- an intermediate stage differential cascode amplifier, in said first operational mode, said intermediate stage cascode amplifier being biased to cut-off, in said second operational mode, said emitter-follower amplifier having a differential output connected as input to said intermediate stage differential cascode amplifier;
- said intermediate stage differential cascode amplifier, in said second operational mode, having an output connected as input to said output stage differential amplifier.
Dependencies are inferred from the claim text.