Differential circuit compensating gain enhancement due to self heating of transistors
AssigneeSumitomo Electric Industries, Ltd.
InventorsKeiji Tanaka, Akihiro Moto, Yoshiyuki Sugimoto
Life of this patent
Estimating the term…
Abstract
A differential circuit with a function to compensate the gain enhancement due to the self-heating of the transistor is disclosed. The differential circuit includes an equalizer unit coupled with one of paired transistors. The other of the paired transistor receives the input signal to be amplified. The base level, or the base-emitter bias, is oppositely modulated by the input signal through the common emitter, which causes the modification of the base current. The equalizer unit reduces the variation of the base level only in low frequencies where the self-heating effect of the transistor appears.
Claims17
A differential circuit for receiving input signals complementary to each other and outputting output signals complementary to each other, the differential circuit comprising:
- a first differential unit including a pair of transistors, one of the transistors in the first differential unit receiving one of the input signals, wherein at least an other of the transistors in the first differential unit shows a gain enhancement in frequencies lower than a transition frequency;
- a second differential unit including a pair of transistors, one of the transistors in the second differential unit receiving another of the input signals, wherein at least an other of the transistors in the second transistor unit shows the gain enhancement in frequencies lower than the transition frequency;
- a first filter for providing an average of said input signals to the other of the transistors in the first differential unit by providing a first compensating signal to said other of the transistors in the first differential unit, the first compensating signal being in phase with the one of the input signals;
- and
- a second lifter for providing the average to the other of the transistors in the second differential unit by providing a second compensating signal to said other of the transistors in the second differential unit, the second compensating signal being in phase with the another of the input signals.
A differential circuit for amplifying input signals to generate output signals, the input signals and the output signals having a configuration of a differential signal, the differential circuit comprising:
- a pair of transistors, one of the transistors receiving one of the input signals, and an other of the transistors receiving an average of the input signals, at least the other of the transistors showing a gain enhancement in frequencies below a transition frequency;
- and
- a filter having a cut-off frequency, the filter providing the average of the input signals to the another other of the transistors,
- wherein the cut-off frequency is substantially equal to or less than the transition frequency.
A differential circuit for amplifying input signals configured with a differential mode, the differential circuit comprising:
- a first differential unit for receiving one of the input signals, the first differential unit showing a gain enhancement in frequencies below a transition frequency;
- a second differential unit for receiving another of the input signals, the second differential unit showing a gain enhancement in frequencies below the transition frequency;
- and
- an equalizer unit for providing a first compensating signal to the first differential unit and a second compensating signal to the second differential unit by receiving an average of the input signals, the equalizer unit including a first filter and a second filter, the first filter generating the first compensating signal from the average of the input signals, and the second filter generating the second compensating signal from the average of the input signals,
- wherein the first compensating signal and the second compensating signal are effective in frequencies below the transition frequency.
Dependencies are inferred from the claim text.