HA17301P

4

HA17301P Application Examples

The HA17301P is a quad operational amplifier, and consists of four operational amplifier circuits and one

bias current circuit. The HA17301P features a wide operating temperature range, single-voltage power

supply operation, internal phase compensation, a wide zero-cross bandwidth, a low input bias current, and a

high open-loop gain. Thus the HA17301P can be used in a wide range of applications. This section

describes several applications using the HA17301P.

HA17301 Circuit Operation

3 pF

GND

Op amp 1

Inverting input

3

Non inverting

input

2

Output

4

Bias circuit

Figure 1 HA17301 Internal Equivalent Circuit

Figure 1 shows the internal equivalent circuit for the HA17301P bias circuit and one operational amplifier

circuit (Op amp 1).

Op amp 1 is basically an emitter ground type operational amplifier in which the input transistor Q

buffer transistor Q

current source transistor Q

transistor Q

gain even at low power-supply voltages. Next, the emitter-follower transistor Q

impedance of this circuit. The use of the power-supply transistor Q

extremely large dynamic range, and essentially an amplitude from ground to (V

Also, the buffer transistor Q

level. Since the capacitor C

circuit, no external compensation is required.

Now consider the non inverting circuit. Assuming that the current amplification ratio provided by Q

adequately large for the current flowing into the non inverting input, then all that current will flow through

diode D

emitter junction. Therefore, if D

Q

to the input current will flow in the Q

This is called a “current mirror”, and when an external

feedback resistor is used, a current equal to the non inverting input current will flow in this resistor and thus

determine the output voltage.