Preamplification circuit

A pre-amplification circuit including:

• a current to voltage conversion and amplification first circuit;
• a second circuit receiving an output signal transmitted from said first circuit, as an input signal;
• a voltage-depended variable capacitance third circuit which is electrically connected to an input of said first circuit, and which a part of a current running into said input of said first circuit enters,
• said third circuit including a diode electrically connected between said input of said first circuit and a grounded voltage, and having a capacitance variable in accordance with a voltage;
• and
• a feedback resistor (4) electrically connected between said input of said first circuit and said second circuit and, wherein,
• said capacitance variable in accordance with a voltage is a first power source,
• the first circuit comprises a first transistor (5) and a first resistor (6), the first resistor electrically connected at one end to a second power source (17) and at another end to both a collector of the first transistor and a base of a second transistor (8),
• a base of the first transistor providing an input terminal of the pre-amplification circuit, and
• the second circuit is an emitter follower buffer stage comprising the second transistor, a third transistor (10), a fourth transistor (12), a second resistor (7), a third resistor (9), a fourth resistor (11), and a fifth resistor (13),
• the second transistor has a collector electrically connected to a third power source (21), an emitter electrically connected to a base of the third transistor and the second resistor, and a base electrically connected to a node at which the first resistor and the collector of the first transistor are electrically connected to each other, the second transistor and the second resistor comprising a first emitter follower buffer circuit.

A pre-amplification circuit including:

• a current to voltage conversion and amplification first circuit;
• a second circuit receiving an output signal transmitted from said first circuit, as an input signal;
• a voltage dependent variable capacitance third circuit which is electrically connected to an input of said first circuit, and which a part of a current running into said input of said first circuit enters,
• said third circuit including a circuit electrically connected between said input of said first circuit and a grounded voltage, and comprised of a diode and a first power source electrically in series to each other, wherein,
• the first circuit comprises a first transistor (5) and a first resistor (6), the first resistor electrically connected at one end to a second power source (17) and at another end to both a collector of the first transistor and a base of a second transistor (8)
• a base of the first transistor providing an input terminal of the preamplification circuit, and
• the second circuit is an emitter follower buffer stage comprising the second transistor, a third transistor (10), a fourth transistor (12), a second resistor (7), a third resistor (9), a fourth resistor (11), and a. fifth resistor (13),
• the second transistor has a collector electrically connected to a third power source (21), an emitter electrically connected to a base of the third transistor and the second resistor, and a base electrically connected to a node at which the first resistor and the collector of the first transistor are electrically connected to each other, the second transistor and the second resistor comprising a first emitter follower buffer circuit.