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Analog Electronics Workshop (AEW). Sep 14, 2013 Rev 1.3. Contents. Intro to Tools Input Offset Input and Output Limits Bandwidth Slew Rate Noise EMIRR Filtering. Vos and Ib. Ex 1.1: Hand Calculations.

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Analog Electronics Workshop (AEW)

Sep 14, 2013

Rev 1.3

Contents
• Intro to Tools
• Input Offset
• Input and Output Limits
• Bandwidth
• Slew Rate
• Noise
• EMIRR
• Filtering
Ex 1.1: Hand Calculations

1. Use the circuit and the excerpt of the data sheet below to calculate the maximum and tpical offset form vos.

Ex 1.1: Solution to Hand calculation

This term is negligible

Simplified equation has nearly the same result

Ex 2.1: Offset Schematic

Two copies of the same two stage amplifier is on the board. Each two stage amplifier has four jumpers to configure the circuit.

Ex 1.1: Noise and Offset PCB Setup

U0 = OPA2211

U1 = OPA2188

Note for this experiment Rin will be shorted. For the next experiment Rin will be connected between input and GND.

Ex 1.1: Instrument Setup

OPA211

OPA188

211: 127mV

188: 54mV

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the I/O limitations.

Ex 1.1: Expected Results

1. Run a “analysis>dc analysis> calculate nodal voltages>” simulation to determine output offset.

2. How did the simulated results compare to the hand calculated results.

Ex 1.2: Hand Calculations

1. Use the circuit and the excerpt of the data sheet below to calculate the maximum and tpical offset form vos.

Ex 1.2: Amplifier I/O PCB Setup

Install OPA735 into socket U1

Ex 1.2: Expected Results

1. Run a “analysis>dc analysis>calculate nodal voltages>” simulation to determine the output voltage from vos.

2. How did the simulated results compare to the hand calculated results.

Common Mode

And Output Swing

I/O Limits

Ex 2.1: Hand Calculations

1. Use excerpt from data sheet below to fill in table:

2. In this example is the limitation from input common mode range or output swing range?

Ex 2.1: Common Mode & Output Swing Schematic

U1 is configured as a buffer for these examples. R6 is not installed and R5 is a short.

In the top position J1 will connect the scope channel 0 to the output of U1 (as shown). In the bottom connection scope channel 0 is connected to the input signal for U2.

U2 is configured in a gain of -34.8. This circuit will be used for bandwidth tests.

The myDAQ provides +/-15V dc supplies. The circuit to the left is used to regulate the supplies to +/-2.5V.

Ex 2.1: Amplifier I/O PCB Setup

Install OPA735 into socket U1

Set jumper J2 to top position

U1 Out to AI(0+)

Ex 2.1: Instrument Setup

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the I/O limitations.

Ex 2.1: Expected Results

Tina Results

myDAQ Results

Run transient analysis with the Tina circuit called “02-AWE-OPA735.TSC”

1. Use the cursors on the myDAQ and Tina Spice tool to measure the amplitude of the clipped signal.

Ex 2.2: Hand Calculations

1. Use excerpt from data sheet below to fill in table:

2. In this example is the limitation from input common mode range or output swing range?

Ex 2.2: Instrument Setup

Install OPA277 into socket U2

Set jumper J2 to bottom position signal generator and scope to input

Ex 2.2: Instrument Setup

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the I/O limitations.

Ex 2.2: Expected Results

1. Use the cursors on the myDAQ and Tina Spice tool to measure the amplitude of the clipped signal.

Ex 3.1: Hand Calculations

1. Determine the bandwidth for the circuit below. Draw the closed loop gain (in dB) vs. frequency.

Ex 3.1: Slew Rate PCB Schematic

U1 is configured as a buffer for these examples. R6 is not installed and R5 is a short.

In the top position J1 will connect the scope channel 0 to the output of U1 (as shown). In the bottom connection scope channel 0 is connected to the input signal for U2.

U2 is configured in a gain of -34.8. This circuit will be used for bandwidth tests.

The myDAQ provides +/-15V dc supplies. The circuit to the left is used to regulate the supplies to +/-2.5V.

Ex 3.2: Instrument Setup

Install OPA333 into socket U1

Set jumper J2 to bottom position signal generator and scope to input

Ex 3.1: Instrument Setup

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the bandwidth limitations. Use the curser to determine the bandwidth (-3dB).

Ex 3.1: Expected Results

Tina Results

myDAQ Results

Run transient analysis with the Tina circuit called “03-AWE-OPA333-BW.tsc”

1. Use the cursors on the myDAQ and Tina Spice tool to measure the bandwidth.

Ex 4.1: Hand Calculations

1. Draw the output waveform for the circuit below.

Ex 4.1: Slew Rate PCB Schematic

U1 is configured as a buffer for these examples. R6 is not installed and R5 is a short.

In the top position J1 will connect the scope channel 0 to the output of U1 (as shown). In the bottom connection scope channel 0 is connected to the input signal for U2.

U2 is configured in a gain of -34.8. This circuit will be used for bandwidth tests.

The myDAQ provides +/-15V dc supplies. The circuit to the left is used to regulate the supplies to +/-2.5V.

Ex 4.1: Amplifier I/O PCB Setup

Install OPA735 into socket U1

Set jumper J2 to top position

U1 Out to AI(0+)

Ex 4.1: Instrument Setup

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the slew rate limitations.

Ex 4.1: Expected Results

Tina Results

myDAQ Results

Run transient analysis with the Tina circuit called “04-AWE-opa333-SR.tsc”

1. Use the cursors on the myDAQ and Tina Spice tool to measure the slew rate (rise / run).

Ex 5.1: Hand Calculations

1. Determine the total rms and peak-to-peak output noise. Note: the switches are as shown (SW3 open, SW2 to GND).

Ex 5.1 Solution to Hand Calc

This could be read from the resistor noise chart.

Current noise and resistor noise are significant in this example. Reducing Rn would help overall noise.

High first stage gain so ignore noise from second stage.

Cutoff frequency is much higher then noise corner so ignore flicker.

Ex 5.1: Noise Schematic

Two copies of the same two stage amplifier is on the board. Each two stage amplifier has four jumpers to configure the circuit.

Ex 5.1: Amplifier I/O PCB Setup

U0 = OPA2211

U1 = OPA2188

Note for this experiment Rin will be shorted. For the next experiment Rin will be connected between input and GND.

Ex 5.1: Instrument Setup

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the bandwidth limitations. Use the curser to determine the bandwidth (-3dB).

Ex 5.1: Expected Results

Tina Results

myDAQ Results

1. Use the cursors on the myDAQ and Tina Spice tool to measure the slew rate (rise / run).

Ex 5.2: Hand Calculations

1. Determine the total rms and peak-to-peak output noise. Note: the switches are as shown (SW3 closed, SW2 to GND). C1 & R8 form a filter.

Ex 5.2: Noise PCB Setup

U0 = OPA211

U1 = OPA277

Note for this experiment Rin will be shorted. For the next experiment Rin will be connected between input and GND.

Ex 5.2: Instrument Setup

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the bandwidth limitations. Use the curser to determine the bandwidth (-3dB).

Ex 5.1: Expected Results

Tina Results

myDAQ Results

1. Fill in table below. How effective is the filter in reducing noise?

Ex 6.1: Hand Calculations

1. The figures below illustrate the EMIRR for two different op-amps. Assume the same magnitude and frequency (476MHz) of RF signal is applied to the circuit below. H

OPA211 EMIRR

OPA188 EMIRR

Ex 6.1: EMIRR (Noise) Schematic

Two copies of the same two stage amplifier is on the board. Each two stage amplifier has four jumpers to configure the circuit.

Ex 6.1: Amplifier I/O PCB Setup

U0 = OPA2211

U1 = OPA2188

Connect antenna to JMP5 & JMP6.

Ex 6.1: Instrument Setup

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the bandwidth limitations. Use the curser to determine the bandwidth (-3dB).

Ex 6.1: Expected Results

Transceiver Keyed

myDAQ Results

OPA211 output offset

2V/div

OPA188 output offset

20mV/div

1. Does the relative change in offset match the theoretical EMIRR plots from the hand calculations?

Ex 7.1: Hand Calculations

1. Simulate the open loop frequency response of the circuit below (answer given). Find the frequency that we should add the zero (70.37kHz). What is the phase margin?

Ex 7.1: Hand Calculations

1. Use result from previous page to compute Riso (answer given):

1. Simulate open loop response (1/beta and Aol). Find the phase margin (83.6 deg).

Ex 7.1: Simulation

1. Simulate the transient response with and without Riso.

SW1

Closed

SW1

Open

Ex 7.1: Amplifier I/O PCB Setup

Install OPA627 into socket U1

Ex 7.1: Instrument Setup

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the I/O limitations.

Ex 7.1: Expected Results (no Riso)

Tina Results

myDAQ Results

Ex 7.2: Hand Calculations

1. The problem with this circuit is that Riso and RL form a voltage divider. With a 100mV input step, what output would you expect? Do hand calculation and use simulation with cursors to confirm the measurement. Note: the dual feedback-Riso circuit shown on the next page will solve the voltage divider issue.

Ex 7.2: Stability PCB Schematic

Solves the issue with drop on Riso.

Ex 7.2: Instrument Setup

Install OPA627 into socket U2

Ex 7.2: Instrument Setup

The instrument setup above will configure the signal source and scope for the circuit below so that we can see the I/O limitations.

Ex 7.2: Expected Results

Riso+DF

Riso

1. The figure above show the results for both the Riso and the DF-Riso. Why is the the peak-to-peak output is different ?

Active

Filters

8.0 Goal of Filter Lab
• Use Filter Pro to design a Sallen-Key and Multiple Feedback filter
• Simulate Sallen Key and Multiple Feedback filters using OPA170 and OPA241
• Sallen Key more sensitive to low GBW.
• MFB less sensitive to low GBW.
• OPA170, GBW = 1.2MHz
• OPA241, GBW = 35kHz
• Measure Sallen Key and Multiple feedback filters with both op-amps.
• Demonstrate that MFB is less sensative then Sallen Key (both measured and simulated)
8.4 Hardware Setup

Set both sets of jumpers to S-K to test the Sallen-Key configuration and to MFB for Multiple Feedback.

Insert OPA170 into the socket and test both Multiple Feedback and Sallen –Key.

Ex 8.4: Instrument Setup

The instrument setup above can be used for all the active filter measurements. Use the cursors to determine the cutoff frequency (-3dB point). In this example