March 2015 - The Circuit Design Blog

Graeme Double Integrator

By placing the poles of two Tee networks (R1, C1, R2 & C2, R3, C3) at the same frequency, U1 performs double integration of its input signal Vin. The gain of the circuit is dependent on the values of the R & C values. For additional information, see “Applications of Operational Amplifiers- Third- generation Techniques” by Jerald G. Graeme. In the absence of system feedback, R4 is used to close the loop to establish a DC operating point. It is not necessary in actual operation. (Circuit is created by Neil P. Albaugh, TI – Tucson)

Graeme Double Integrator circuit:

Graemble Double Integrator — Graeme Double Integrator

Online Simulation of the “Graeme Double Integrator” Circuit

The great feature of the TINA circuit simulator that you can analyze this circuit immediately with TINACloud the online version of TINA. Of course you can also run this circuit in the off-line version of TINA.

Click here to invoke TINACloud and analyze the circuit, or watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

1kHz 2nd-Order Bessel High-Pass Filter

This filter was designed using TI’s “FilterPro” software. The cutoff frequency and gain can be changed by editing this circuit with new RC values determined by FilterPro. This filter topology is inherently a phase inverting configuration. For a non- inverting low- pass filter use a Sallen- Key type. As shown, this filter is designed for use on a single power supply. For bipolar supplies, Voffset is not needed. Large value resistors– typical in low frequency filters– require a CMOS or JFET input op amp to minimize offset voltage errors. (Circuit is created by Neil P. Albaugh TI-Tucson)

1kHz 2nd-Order Bessel High-Pass Filter circuit:

Online Simulation of the “1kHz 2nd-Order Bessel High-Pass Filter” Circuit

Click here to invoke TINACloud and analyze the circuit, or watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

Speech Compression Amplifier With Linear Gain = 20V/V

Compression amplifiers are frequently used to prevent overmodulation of AM transmitters. This prevents the creation of spurious modulation products called “splatter”. The “soft knee” of the transfer curve also imparts a “vacuum tube- like” sound to audio signals and musical instruments. The brightness of the LEDs indicate the degree of compression. Bypass capacitors are not shown. (Circuit is created by Neil P. Albaugh, TI-Tucson)

Speech Compression Amplifier With Linear Gain = 20V/V circuit:

Online Simulation of the “Speech Compression Amplifier With Linear Gain = 20V/V” Circuit

Click here to invoke TINACloud and analyze the circuit, or watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

1 kHz Wien-Bridge Oscillator

The starting pulse is generated by the positive power supply’s startup slope. If the power supply does not slew fast enough the oscillator will not start. R3 can be increased to increase the gain and likelihood of starting. It also increases distortion when the amplitude as the peaks aproach the power supply rails. (Circuit is created by John Bishop based on a design by Neil P. Albaugh.)

1 kHz Wien-Bridge Oscillator circuit:

Online Simulation of the “1 kHz Wien-Bridge Oscillator” Circuit

Click here to invoke TINACloud and analyze the circuit, or watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com

Bridge Sensor Amplifier With RFI Filter

This high accuracy bridge sensor amplifier is based on the autozero INA326 instrumentation amplifier. Bridge sensors are commonly found in pressure transducers, weigh scales, strain guages, and load cells. As shown, the amplifier gain is 200V/V. Capacitors C1 & C2 form a 2nd order 1kHz low- pass filter to reduce noise. The INA326 is virtually free of 1/f noise. R8 & R9 together with C4, C5, & C6 form an RFI filter. For best filtering, make R8 = R9 and C5 = C6 as close as possible. C4 = C5 * 10. In battery- operated applications, an INA327 with shutdown is recommended. For operation over -40C to +125C, use an INA337. (Circuit is created by Neil P. Albaugh, TI-Tucson)

The “Bridge Sensor Amplifier With RFI Filter” circuit:

Online Simulation of the “Bridge Sensor Amplifier With RFI Filter” Circuit

Click here to invoke TINACloud and analyze the circuit, or watch our tutorial video!

You can send this link to any TINACloud customers and they can immediatelly load it by a single click and then run using TINACloud.

Michael Koltai
www.tina.com