U3751

The Advantest U3751 is a compact, lightweight 8 GHz portable spectrum analyzer optimized for both production line and field maintenance applications. Incorporating advanced digital IF technology for outstanding level measurement reproducibility, the U3751 offers twice the processing speed of predecessor models and features standard LAN connectivity, a 5-minute warm-up time, and a versatile 3-way power supply that supports AC, DC, and battery operation.

RF and Microwave Signal Analysis

Specifications

General

Parameter	Value
Interfaces	LAN, USB (Type A, Type B), VGA output (standard); GPIB (optional)
Display	6.5-inch color TFT LCD, 640 × 480 (VGA) resolution
Warm-Up Time	5 minutes

Physical

Parameter	Value
Power Supply	100 V to 240 V AC (50 Hz/60 Hz); 11 V to 17 V DC; Battery pack
Operating Temperature	0 °C to +50 °C
Dimensions (W×H×D)	308 mm × 175 mm × 209 mm
Weight	5.6

Frequency Specifications

Parameter	Value
Frequency Range	9 kHz to 8 GHz
Frequency Span Range	Zero span, 10 kHz to 8 GHz
Reference Frequency Accuracy	±2 × 10^-6 / year (standard), ±1 × 10^-7 / year (with Opt 20)
Aging Rate Per Year	±2 × 10^-6 / year
Frequency Temperature Stability	±2.5 × 10^-6 (0 °C to +50 °C)

Resolution and Bandwidth

Parameter	Value
Resolution Bandwidth (RBW) Range	100 Hz to 1 MHz (standard, 1-3 step); 30 Hz to 1 MHz / 3 MHz (with Opt 70)
Video Bandwidth (VBW) Range	10 Hz to 1 MHz (1-3 step)

Signal Processing and Measurements

Parameter	Value
Trace Detectors	Normal, Positive Peak, Negative Peak, Sample, RMS

Inputs and Outputs

Parameter	Value
RF Input Impedance	50 Ω
RF Input Connector	N (female)

Physical and Power

Parameter	Value
AC Input Voltage Range	100 V to 240 V AC
AC Input Frequency	50 Hz / 60 Hz
DC Input Voltage Range	11 V to 17 V DC

Environmental and Compliance

Parameter	Value
Storage Temperature Range	-20 °C to +60 °C

Options and Accessories

Parameter	Value
Option 10	2 Channel Input (50 Ω, 3 GHz)
Option 11	2 Channel Input (75 Ω, 2.2 GHz)
Option 15	1 Channel Input (75 Ω)
Option 20	High-Stability Frequency Reference Source
Option 28	EMC Filter
Option 53	Time-Domain Analysis (1 ch)
Option 54	Time-Domain Analysis (2 ch)
Option 55	Wide-Band Time-Domain Analysis (1 ch)
Option 70	High-Purity Spectrum Analysis (Resolution Bandwidth 30 Hz to 1 / 3 MHz - U3741 / U3751)
Option 75	Tracking Generator (75 Ω, 2.2 GHz)
Option 76	Tracking Generator (50 Ω, 3 GHz)
Option 77	Tracking Generator (50 Ω, 6 GHz)

Frequency

Parameter	Value
Phase Noise	≤ -85 dBc/Hz (at 10 kHz offset, 1 GHz carrier) (standard); ≤ -100 dBc/Hz (with Opt 70)
Span Accuracy	±1%

Amplitude

Parameter	Value
Displayed Average Noise Level (DANL)	≤ -115 dBm (10 MHz to 8 GHz, RBW 100 Hz, preamplifier OFF)
DANL with Preamplifier (Option 20)	≤ -135 dBm (10 MHz to 3 GHz), ≤ -130 dBm (3 GHz to 8 GHz) (RBW 100 Hz, preamplifier ON)
Maximum Safe Input Level	+30 dBm (with attenuator ≥ 20 dB), 0 VDC
Input Attenuator Range	0 to 50 dB (10 dB steps)

Sweep

Parameter	Value
Sweep Time Range	2 ms to 1000 s (Span > 0 Hz), 50 µs to 1000 s (Zero Span)

Performance

Parameter	Value
1 dB Gain Compression	>= -10 dBm (10 MHz to 8 GHz)
RF Input VSWR	1.5 or less (10 MHz to 3 GHz, input attenuator >= 10 dB), 2.0 or less (3 GHz to 8 GHz, input attenuator >= 10 dB)
Frequency Response Flatness	+/- 1.0 dB (9 kHz to 3.1 GHz), +/- 1.5 dB (3.1 GHz to 8 GHz)

Accuracy

Parameter	Value
Absolute Amplitude Accuracy	+/- 0.8 dB (at 20 MHz, calibrator output level)

Protection

Parameter	Value
Maximum DC Input Voltage	+/- 50 VDC

Inputs & Outputs

Parameter	Value
Calibration Signal Output	20 MHz, -20 dBm +/- 0.3 dB

Technology

Superheterodyne Spectrum Analysis

Applications

RF and microwave spectrum analysis, field maintenance, production-line testing, and EMC pre-compliance