SRS SR844 — 200 MHz锁相放大器
- 25 kHz至200 MHz范围
- 80 dB动态储备
- 时间常数从100 s到30 ks
(6、12、18或24 dB/oct衰减) - “无时间常数”模式
- 自动增益、相位、储备和失调
- 内部或外部参考
- 两个16位DAC和ADC
- GPIB和RS-232接口
概观
| SR844是SRS公司提供的最宽带宽锁相放大器。它提供无与伦比的性能，频率范围为25 kHz至200 MHz，无漂移动态储备高达80 dB。SR844包括SRS DSP的众多特性、易操作性和可编程性锁相放大器. |
SR844 200 MHz锁相放大器
SR844是SRS公司提供的最宽带宽锁相放大器。它提供无与伦比的性能，频率范围为25 kHz至200 MHz，无漂移动态储备高达80 dB。SR844包括SRS DSP的众多特性、易操作性和可编程性锁相放大器.
数字技术
SR844使用与SR850、SR830和SR810相同的高级DSP技术锁相放大器。与模拟仪器相比，DSP具有许多优势——高动态储备、低零点漂移、精确的RF相移和正交性，以及数字输出滤波。
信号输入
SR844具有50ω和1mω两种输入。1mω输入用于低频下的高源阻抗，或标准10倍示波器探头。50ω输入提供最佳RF信号匹配。全尺寸灵敏度范围从1 Vrms (+13 dBm)到100 nVrms (-127 dBm)。最高可选择60 dB的RF衰减或20 dB的RF增益，增量为20 dB。增益分配可以优化，以提供最高80 dB的动态储备。
SR844 Specifications | |
Signal Channel | |
| Voltage input | Single-ended BNC |
| Input impedance | 50 Ω or 1 MΩ + 30 pF |
| Damage threshold | ±5 V (DC + AC) |
| Bandwidth | 25 kHz to 200 MHz |
| Sensitivity | |
| <1 MHz | 100 nVrms to 1 Vrms full scale |
| <50 MHz | 1 µVrms to 1 Vrms full scale |
| <200 MHz | 10 µVrms to 1 Vrms full scale |
| Gain accuracy | |
| <50 MHz | ± 0.25 dB |
| <200 MHz | ± 0.50 dB |
| Gain stability | 0.2 %/°C |
| Coherent pickup | Low noise reserve, sensitivity <30 mV |
| f < 10 MHz | <100 nV (typ.) |
| f < 50 MHz | <2.5 µV (typ.) |
| f < 200 MHz | <25 µV (typ.) |
| Input noise (50 Ω) | 2 nV/√Hz (typ.), 8 nV/√Hz (max.) |
| Input noise (1 MΩ), | 5 nV/√Hz (typ.), 8 nV/√Hz (max.) |
| Dynamic reserve | up to 80 dB |
Reference Channel | |
| External reference input | 25 kHz to 200 MHz |
| Impedance | 50 Ω or 10 kΩ + 40 pF |
| Level | 0.7 Vpp pulse or 0 dBm sine |
| Pulse width | >2 ns at any frequency |
| Threshold setting | Automatic, midpoint of waveform |
| Acquisition time | <10 s (auto-ranging, any frequency) <1 s (within same octave) |
| Internal reference | 25 kHz to 200 MHz |
| Frequency resolution | 3 digits |
| Frequency accuracy | ±0.1 in the 3rd digit |
| Harmonic detection | 2F (50 kHz to 200 MHz) |
| Reference outputs | Phase locked to Int. or Ext. reference |
| Front panel ref output | 25 kHz to 200 MHz square wave. 1.0 Vpp nominal into 50 Ω |
| Rear panel TTL output | 25 kHz to 1.5 MHz, 0 to +5 V nominal, ≥3 V into 50 Ω |
| Phase resolution | 0.02° |
| Absolute phase error | |
| <50 MHz | <2.5° |
| <100 MHz | <5.0° |
| <200 MHz | <10.0° |
| Rel. phase error, orthog. | <2.5° |
| Phase noise (external) | 0.005° rms at 100 MHz (100 ms time constant) |
| Phase drift | |
| <10 MHz | <0.1°/°C |
| <100 MHz | <0.25°/°C |
| <200 MHz | <0.5°/°C |
Demodulator | |
| Zero stability | Digital displays have no zero-drift. Analog outputs have <5 ppm/°C drift for all dynamic reserve settings. |
| Time constants | 100 µs to 30 ks with 6, 12, 18 or 24 dB/octave rolloff |
| ”No Filter” mode | 10 to 20 µs update rate (X and Y) |
| Harmonic rejection | |
| Odd harmonics | -9.5 dBc @3 × ref, -14 dBc @5 × ref, etc. (20log 1/n where n = 3, 5, 7, 9…) |
| Even harmonics | <-40 dBc |
| Sub-harmonics | <-40 dBc |
| Spurious responses | -10 dBc @ ref ± 2 × IF -23 dBc @ ref ± 4 ×IF <-30 dBc otherwise |
Displays | |
| Channel 1 | |
| Type | 4½-digit LED with 40-segment bar graph |
| Quantities | X, R (V or dBm), X-noise, Aux In 1 |
| Channel 2 | |
| Type | 4½-digit LED with 40-segment bar graph |
| Quantities | Y, Θ, Y-noise (V or dBm), Aux In 2 |
| Expand | ×10 or ×100 for Ch1 and Ch2 |
| Ratio | X and Y ratioed with respect to Aux In 1 or Aux In 2 before filtering and computation of R. The ratio input is normalized to 1 V and has a dynamic range greater than 100. |
| 参考 | |
| Type | 4½-digit LED |
| Quantities | Reference Frequency, Phase, Offsets, Aux Out, IF Frequency, Elapsed Time |
Channel 1 and Channel 2 Outputs | |
| Voltage range | ±10 V full scale proportional to X, Y or CH1, CH2 displayed quantity |
| Update Rate | |
| X, Y | 48 to 96 kHz |
| R, Θ, Aux inputs | 12 to 24 kHz |
| X-noise, Y-noise | 512 Hz |
Auxiliary Inputs and Outputs | |
| Inputs | 2 |
| Type | Differential, 1 MΩ |
| Range | ±10 V |
| Resolution | 0.33 mV |
| Bandwidth | 3 kHz |
| Outputs | 2 |
| Range | ±10 V |
| Resolution | 1 mV |
| Data Buffers | Two 16,000 point buffers. Data is recorded at rates up to 512 Hz and is read using the computer interfaces. |
General | |
| Interfaces | IEEE-488.2 and RS-232 interfaces are standard. All instrument functions can be controlled and read through the interfaces. |
| Power | 70 W, 100/120/220/240 VAC, 50/60 Hz |
| Dimensions | 17″ × 5.25″ × 19.5″ (WHL) |
| Weight | 23 lbs. |
| Warranty | One year parts and labor on defects in materials and workmanship |
