DC–200 MHz Low-Noise Voltage Amplifier with Switchable Gain (20 dB / 40 dB) and Integrated Digital Attenuator
Table of Contents
Overview
The DC–200 MHz Low-Noise Voltage Amplifier is a custom-built, high-performance signal conditioning solution designed for ultra-low noise and wideband applications. The system integrates a high-gain low-noise amplifier (LNA) and a digitally controlled attenuator, providing flexible gain control while maintaining excellent signal integrity.
The design consists of two core modules:
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43 dB Low-Noise Amplifier (DC–200 MHz bandwidth)
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31 dB Digitally Controlled Attenuator (1 dB step resolution)
The amplifier provides a default 40 dB gain configuration, with internal 20 dB attenuation capability and additional programmable output attenuation. This ensures compatibility with sensitive ADC inputs and prevents saturation by allowing precise signal level adjustment.
Designed for laboratory, instrumentation, and high-speed data acquisition systems, the amplifier operates from a single +12 V supply and features 50 Ω input/output impedance with DC coupling throughout the signal path.
Features
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Wideband operation: DC to 200 MHz
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Ultra-low input noise: Target 1.2 nV/√Hz
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Switchable gain levels: 20 dB (×10) and 40 dB (×100)
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Integrated 31 dB digitally controlled attenuator (1 dB step)
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Internal attenuation option for gain flexibility
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Fast rise/fall time: ≤ 1.8 ns
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50 Ω input and output impedance
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DC-coupled signal path
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Single +12 V power supply operation
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SMA connectors for RF signal input/output
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Compact modular architecture
Specifications
- Operating Frequency: DC ~ 200 MHz
- Amplification Gain: 20 dB ~ 40 dB (customer configurable)
- In-Band Gain Flatness: ≤ ±0.5 dB
- Input/Output VSWR: ≤ 1.5
- Noise Figure: ≤ 0.8 dB
- Attenuation Interface: Floating or grounded
- Grounded: no attenuation
- Floating: 20 dB attenuation
- Connector Type: SMA-50KFD
- Input/Output Impedance: 50 Ω
- Operating Temperature: -10 ~ +70 °C
- Power Supply: +8 V ~ +17 V
- Operating Current: ≤ 150 mA
Gain Adjustment and Attenuation Settings of the Low-Noise Amplifier Module
| 5 | 4 | 3 | 2 | 1 | Attenuation value (dB) |
| 0 | 0 | 0 | 0 | 0 | 31 |
| 0 | 0 | 0 | 0 | 1 | 30 |
| 0 | 0 | 0 | 1 | 0 | 29 |
| 0 | 0 | 0 | 1 | 1 | 28 |
| 0 | 0 | 1 | 0 | 0 | 27 |
| 0 | 0 | 1 | 0 | 1 | 26 |
| 0 | 0 | 1 | 1 | 0 | 25 |
| 0 | 0 | 1 | 1 | 1 | 24 |
| 0 | 1 | 0 | 0 | 0 | 23 |
| 0 | 1 | 0 | 0 | 1 | 22 |
| 0 | 1 | 0 | 1 | 0 | 21 |
| 0 | 1 | 0 | 1 | 1 | 20 |
| 0 | 1 | 1 | 0 | 0 | 19 |
| 0 | 1 | 1 | 0 | 1 | 18 |
| 0 | 1 | 1 | 1 | 0 | 17 |
| 0 | 1 | 1 | 1 | 1 | 16 |
| 1 | 0 | 0 | 0 | 0 | 15 |
| 1 | 0 | 0 | 0 | 1 | 14 |
| 1 | 0 | 0 | 1 | 0 | 13 |
| 1 | 0 | 0 | 1 | 1 | 12 |
| 1 | 0 | 1 | 0 | 0 | 11 |
| 1 | 0 | 1 | 0 | 1 | 10 |
| 1 | 0 | 1 | 1 | 0 | 9 |
| 1 | 0 | 1 | 1 | 1 | 8 |
| 1 | 1 | 0 | 0 | 0 | 7 |
| 1 | 1 | 0 | 0 | 1 | 6 |
| 1 | 1 | 0 | 1 | 0 | 5 |
| 1 | 1 | 0 | 1 | 1 | 4 |
| 1 | 1 | 1 | 0 | 0 | 3 |
| 1 | 1 | 1 | 0 | 1 | 2 |
| 1 | 1 | 1 | 1 | 0 | 1 |
| 1 | 1 | 1 | 1 | 1 | 0 |
Note:
- 1 indicates the switch is ON.
- 0 is the OFF switch.
Applications
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High-speed ADC front-end signal conditioning
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Wideband sensor signal amplification
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Oscilloscope and measurement system enhancement
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RF and IF broadband amplification
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Laboratory instrumentation
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Scientific research and physics experiments
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Low-level signal detection systems
FAQ
Q: What is the digital interface of the 200 MHz amplifier?
A: The amplifier includes a simple digital control input used to switch attenuation levels.
- When the control pin is left floating, the amplifier operates at full gain.
- When the control pin is connected to ground, the signal is attenuated by 20 dB.
This provides an easy way to toggle between gain states (e.g., 20 dB and 40 dB) without requiring complex control circuitry.
Q1: Is the DC–200 MHz amplifier an operational amplifier or an RF low-noise amplifier?
A: This product is an RF low-noise amplifier (LNA), not an operational amplifier. It is specifically designed for high-frequency signal amplification with:
- 50 Ω input/output impedance
- SMA RF connectors
- Wide bandwidth from DC to 200 MHz
Unlike operational amplifiers, which are typically used in low-frequency analog circuits, this amplifier is optimized for RF and high-speed signal applications such as measurement systems and signal conditioning.
Q1: How is the gain switched?
The amplifier supports switchable gain (20 dB / 40 dB) via internal configuration. Gain control can be implemented using hardware switching or digital attenuation depending on system requirements.
Q2: Can the output be attenuated to prevent ADC saturation?
Yes. The design includes a digitally controlled attenuator with 1 dB step resolution (up to 31 dB). This allows precise output level control and prevents ADC overdrive.
Q3: Is the amplifier fully DC-coupled?
Yes. The signal path is DC-coupled from input to output, making it suitable for applications requiring low-frequency or DC signal amplification.
Q4: Does it require dual power supplies?
No. The unit operates from a single +12 V DC power supply.
Q5: Are custom configurations available?
Yes. Gain range, attenuation control method, enclosure type, and connector options can be customized based on your project requirements.
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