Single-Ended In/Single-Ended Out, Utilizing Transformer

3.1 Single-Ended In/Single-Ended Out, Utilizing Transformer

The fully differential amp output can be monitored by a single-ended instrument at J4. The THS4503EVM utilizes Mini-Circuits CD542 footprint transformers to make the fully differential to single-ended conversion. An ADP4−1WT transformer is installed on the board.

R8, R9, and R10 are chosen such that the load on the fully differential amp is 800 Ω when combined with the load impedance transformed by the turn ratio T1. This load is chosen because it is a common input impedance value for ADCs, and is the impedance at which many fully differential amp parameters are measured. The 800-Ω load occurs when one of two conditions is met:

-R11 is installed and the measuring instrument is set to 1-MΩ input impedance

or

-R11 is not installed and the measuring instrument has an input impedance of 50 Ω.

Figure 3−1. Single-Ended In/Single-Ended Out, Utilizing Transformer

J1

Vin−

TP1

Vocm

C13

1 µF

C1 0 R2

374Ω

R1

56.2Ω

C2 0 R3

402Ω

R17

0

R4

392Ω

 

+VS

 

 

 

 

 

 

3

R6 0

R8

 

T1

 

 

4

3

J4

 

U1

 

 

1

4

340Ω

 

 

Vout

 

 

 

2

Vocm

 

R10

5

R11

 

 

 

280Ω

 

8

+

5

R9

 

49.9

 

 

R7 0

6

1

 

 

THS4503

 

 

 

 

 

340Ω

 

 

 

 

6

 

 

ADP4−1WT

 

 

 

 

 

 

−VS

R5

392Ω

3.2 Single-Ended to Fully Differential Application

The schematic of Figure 3−2 shows the proper technique for ac-coupling. The voltage present on the VOCM pin determines the dc operating point of the circuit. When no voltage is connected to TP1, the VOCM voltage level is determined by a voltage divider internal to the op amp, and is approximately equal to half of +VS. This dc voltage is present on both outputs, and also present on both inputs—being connected through R2 and R3.

3-2

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Texas Instruments THS4503EVM manual Single-Ended In/Single-Ended Out, Utilizing Transformer

THS4503EVM specifications

The Texas Instruments THS4503EVM is a high-performance evaluation module designed to showcase the capabilities of the THS4503, a high-speed voltage feedback amplifier. This EVM is ideal for engineers and designers looking to evaluate the performance characteristics of this amplifier in real-world applications, including video signal processing, data acquisition systems, and RF applications.

One of the main features of the THS4503EVM is its exceptional bandwidth performance. The THS4503 amplifier boasts a wide bandwidth that extends up to 1 GHz, making it suitable for applications where high frequency signals need to be processed with minimal distortion. The high slew rate of 3000 V/µs allows for rapid signal changes, ensuring that fast transients are accurately captured without significant overshoot or ringing.

The design of the THS4503EVM also incorporates a low noise characteristic, making it an excellent choice for sensitive applications where signal integrity is paramount. The EVM's Input Voltage Noise Density is remarkably low, contributing to cleaner signal amplification and making it a valuable tool for testing low-level signals.

Another significant characteristic of the THS4503EVM is its flexibility in configuration. The evaluation module is equipped with connectors that allow users to quickly set up various input and output configurations. This provides engineers with the ability to easily test a wide range of operating conditions, including voltage gain settings, power supply configurations, and load conditions, all ideal for diverse application scenarios.

Furthermore, the THS4503EVM supports both single and dual power supply options, accommodating various system designs. It can operate on a supply voltage range from ±2.5 V to ±5 V, allowing users to tailor the functionality of the amplifier to their specific power requirements.

In terms of technology, the THS4503 integrates precision feedback circuitry and advanced manufacturing techniques, ensuring minimal drift and excellent linearity. The module is designed for simplicity and user-friendliness, with comprehensive documentation and application information available from Texas Instruments, aiding users in achieving optimal performance.

In summary, the Texas Instruments THS4503EVM is a powerful evaluation tool for the THS4503 amplifier, featuring high bandwidth, low noise, flexible configuration options, and robust support for various supply voltages. Its capabilities make it an invaluable resource for engineers working across a wide range of high-speed signal applications.