High-frequency amplifier circuit, semiconductor device, and magnetic recording and reproducing device
A high-frequency amplifier circuit includes a balanced-unbalanced converter converting a single-ended signal into differential signals. The output of a first amplifier amplifying the single-ended signal is connected to the signal terminal on the unbalanced side of the balanced-unbalanced converter. The input of a second amplifier amplifying one of the differential signals is connected to one signal terminal on the balanced side of the balanced-unbalanced converter. The input of a third amplifier amplifying another of the differential signals is connected to another signal terminal on the balanced side of the balanced-unbalanced converter. An impedance element is inserted between an element on the balanced side of the balanced-unbalanced converter and a ground.
1. A high-frequency amplifier circuit comprising:
a balanced-unbalanced converter converting a single-ended signal into differential signals, wherein
an output of a first amplifier amplifying the single-ended signal is connected to a signal terminal on an unbalanced side of the balanced-unbalanced converter,
an input of a second amplifier amplifying one of the differential signals is connected to one signal terminal on a balanced side of the balanced-unbalanced converter,
an input of a third amplifier amplifying another of the differential signals is connected to another signal terminal on the balanced side of the balanced-unbalanced converter, and
an impedance element is inserted between an element on the balanced side of the balanced-unbalanced converter and a ground,
wherein the impedance element includes at least on resistive element; and
wherein the impedance element includes a plurality of resistive elements connected in series and, to a front and a back of at least one of the plurality of resistive elements, a wiring line short-circuiting the at least one resistive element or a wiring line including an opening is connected.
2. The high-frequency amplifier circuit according to claim 1 , wherein the impedance element has an impedance that is equal to approximately a quarter of a combined impedance of the second amplifier and the third amplifier.
3. A semiconductor device comprising the high-frequency amplifier circuit according to claim 1 formed therein.
4. A magnetic recording and reproducing device comprising the high-frequency amplifier circuit according to claim 1 mounted therein.
5. A magnetic recording and reproducing device comprising the semiconductor device according to claim 3 mounted therein.
6. A high-frequency amplifier circuit comprising:
a balanced-unbalanced converter converting a single-ended signal into differential signals, wherein
an output of a first amplifier amplifying the single-ended signal is connected to a signal terminal on an unbalanced side of the balanced-unbalanced converter,
an input of a second amplifier amplifying one of the differential signals is connected to one signal terminal on a balanced side of the balanced-unbalanced converter,
an input of a third amplifier amplifying another of the differential signals is connected to another signal terminal on the balanced side of the balanced-unbalanced converter, and
an impedance element is inserted between an element on the balanced side of the balanced-unbalanced converter and a ground,
wherein the impedance element has an impedance that is equal to approximately a quarter of a combined impedance of the second amplifier and the third amplifier.
7. The high-frequency amplifier circuit according to claim 6 , wherein the impedance element includes at least one resistive element.
8. The high-frequency amplifier circuit according to claim 7 , wherein the impedance element includes a plurality of resistive elements connected in series and, to a front and a back of at least one of the plurality of resistive elements, a wiring line short-circuiting the at least one resistive element or a wiring line including an opening is connected.
9. A semiconductor device comprising the high-frequency amplifier circuit according to claim 6 formed therein.
10. A magnetic recording and reproducing device comprising the high-frequency amplifier circuit according to claim 6 mounted therein.
11. A magnetic recording and reproducing device comprising the semiconductor device according to claim 9 mounted therein.