Signal Analyzer with Exceptional Phase Noise Performance for Characterizing Signals

Exceptional Analog Performance…
Anritsu Returns to Spectrum Analyzer Basics

The Signal Analyzer MS2840A has greatly improved phase noise performance forming the key to spectrum analyzer performance.
At -140 dBc/Hz (@150 MHz and 10 kHz offset), the phase noise performance of the middle-price range MS2840A surpasses that of high-end analyzers.

Only expensive high-end spectrum analyzers have excellent phase noise performance. As a result, developers are still relying on legacy spectrum analyzers for good phase noise performance well past the design life. Anritsu has released its Signal Analyzer MS2840A with emphasis on excellent phase noise performance at an affordable price.

To evaluate oscillators and oscillator modules, the affordably priced MS2840A features excellent phase noise performance equivalent to high-end spectrum analyzers.

Phase Noise Performance Positioning

The all-in-one Signal Analyzer MS2840A has everything needed for evaluating analog circuits, especially oscillators, for developing narrowband wireless equipment such as LMR, radar, and analog wireless equipment. Be sure to test it out when purchasing a new analyzer or replacing worn-out legacy models.

Advantages of Switching to Signal Analyzer MS2840A

1.    Better Phase Noise Performance than High-End Analyzers (-140 dBc/Hz)

2.    Higher Level Accuracy and Faster Measurement Speed

3.    One-button Wireless Test Functions for OBW, ACP, etc., and Easy Spurious Tests meeting National Standards

Advantage 1
Better Phase Noise Performance than High-End Analyzers (-140 dBc/Hz)

Combining the Signal Analyzer MS2840A with the Low Phase Noise MS2840A-066 option greatly improves the close-in phase noise performance. Despite being a middle-price range instrument, this excellent MS2840A performance of -140 dBc/Hz (at 150 MHz measurement frequency with 10 kHz offset, meas.*) and -138 dBc/Hz (at 1 GHz measurement frequency with 10 kHz offset, meas.^*) surpasses the performance of expensive high-end analyzers.

Question: What changes with better spectrum analyzer phase noise performance?

Answer: The true value of the signal can be measured.

• Spectrum analyzers measure the signal using frequency conversion (convert RF signal to IF signal). The performance of the oscillator (LO signal) used for this frequency conversion determines the shape of the measured signal (Fig. 1).
• The phase noise performance is a key indicator of the spectrum purity; when it is good, the spectrum waveform is converted faithfully to an IF signal for which the true value can be measured (Fig. 1).

For example, spectrum analyzers with poor phase noise cannot perform measurement when there is spurious or noise near the measured signal. However, these measurements are possible using a spectrum analyzer with good phase noise performance (Fig. 2).

Advantage 2
Higher Level Accuracy and Faster Measurement Speed

The Signal Analyzer MS2840A uses a built-in Anritsu-unique oscillator for calibration to improve the level accuracy compared with legacy high-end analyzers. In addition, combining a Voltage Control Oscillator (VCO) with fast frequency switching with Anritsu-unique circuit technology supports both high-speed sweeping and excellent phase noise performance.

Absolute Amplitude Accuracy (Level Accuracy) Comparison
The level accuracy of legacy spectrum analyzers is determined by individual conditions such as frequency response, amplitude accuracy, etc. Consequently, determining the total level accuracy requires summing these values, but these summed values are not guaranteed values.
On the other hand, the Signal Analyzer MS2840A standardizes the uncertainty of the frequency characteristics, attenuator switching error, and linearity to assure excellent absolute amplitude accuracy (level accuracy) under conditions including these errors.

The Signal Analyzer MS2840A supports measurement with excellent level accuracy even when the frequency and attenuator are changed by calibrating the frequency for all basebands using the Anritsu-unique built-in calibration oscillator.

Unique Level Calibration Technology
Conventional spectrum analyzers generate errors simply by changing the measurement frequency because level calibration is performed for only one frequency point. With the MS2840A, level calibration is performed across a wide frequency range from 9 kHz to 4 GHz using the built-in wideband calibration oscillator, supporting measurements with unprecedentedly high level accuracy across a range of 9 kHz to 4 GHz.

Measurement Speed
Test time is the key issue in a production environment. Even at the R&D stage, it is important to cut test times by speeding-up products.

Legacy high-end analyzers used magnetically tuned YiG-tuned oscillators (YTO) to improve phase noise performance. Changing frequency is achieved with a YTO by Adjusting the current in the magnet. Fast adjustments require very high current steps.

In comparison, recent signal analyzers use a voltage-controlled oscillator (VCO). Although a VCO supports fast frequency switching, its phase noise performance is generally worse than the YTO. The Signal Analyzer MS2840A achieves both low phase noise and high sweep speed by using a new synthesizer circuit design to solve these problems of legacy analyzers with YTOs.

Comparison of Spectrum Analyzer Sweep Speed (Measurement Conditions: Start Frequency = 0 Hz, Stop Frequency = 6 GHz, RBW = VBW = 1 MHz)
This section compares the sweep speed of two legacy high-end analyzers using a YTO with the MS2840A sweep speed. The sweep speed of the MS2840A is five times faster than Analyzer 2. At measurements such as spurious measurement requiring sweeping, this massive increase in sweep speed is a key factor in cutting test times.

Advantage 3
One-button Wireless Test Functions for OBW, ACP, etc., and Easy Spurious Tests meeting National Standards

The MS2840A has built-in wireless test functions covering each standard which can be executed by specifying the measurement parameter and pressing one button.
In particular, since the built-in Spurious Emission measurement function uses a frequency capture function with zero span as described by the standard, rather than using spurious sweeping (search), the previously difficult-to-use zero-span capture method is greatly simplified.

Spurious Emissions
For spurious (unwanted emission power) measurements, when the measured value of the spurious components found by Peak Search exceeds the permissible value, the frequency sweep width is gradually narrowed to accurately measure the frequency of those components and then finally the spurious amplitude average is measured as the frequency sweep becomes 0 Hz (zero span). To simplify this difficult measurement procedure, the MS2840A Spurious Emission function performs this measurement automatically using zero span without searching.
The frequency range is divided into as many as 20 sweep segments, the measurement parameters and limit lines are specified, and the peak power in each segment as well as the limit-line margin are measured with the evaluation results displayed as PASS/FAIL.

Frequency Counter
The frequency of unmodulated waveforms can be measured using the Frequency Counter function of the Marker function. The Frequency Counter measurement time is set using the Gate Time.

Channel Power
The channel bandwidth power is measured by selecting three filter types (Rect, Nyquist, and Root Nyquist).
The parameters are easily set using built-in templates for each standard.

OBW (Occupied Bandwidth)
The occupied bandwidth is measured by selecting either the N% mode or X dB mode. The parameters are easily set using built-in templates for each standard.

ACP (Adjacent Channel Leakage Power)
The adjacent channel leakage power (ACP) measures the power of the adjacent channel (offset) to the carrier frequency. The In-Band can be set for carrier 1 thru 12 and switching is performed instantaneously at the screen.
The parameters are set easily using built-in templates for each standard.

Spectrum Emission Mask
This function measures the peak power for each section and the limit-line margin by dividing the offset into 12 sections (max.) and specifying the measurement parameters and limit line. The evaluation results are displayed as PASS/FAIL at the bottom-left of the screen.
The parameters are set easily using built-in templates for each standard.

Burst Average Power
The burst average power measurement displays the average power within a range specified by two markers on the time-domain screen.
The parameters are set easily using built-in templates for each standard.

Third Order Intercept (TOI)
The third order intercept (TOI) is calculated from the two-signal third-order distortion caused by the non-linearity of the device under test (DUT), which is generated near the required waveform by inputting two CW signals (required) with different frequencies.

CCDF/APD
The complementary cumulative distribution function (CCDF) and the amplitude probability density (APD) display the probability of the power deviation on the vertical axis and the power deviation on the horizontal axis to verify the DUT signal CCDF and APD.
CCDF: Measures and displays cumulative distribution of instantaneous power deviations vs average power
APD: Measures and displays probability distribution of instantaneous power deviations vs average power

Phase Noise Measurement Function (Option)
This function uses the excellent close-in phase noise performance of the MS2840A to measure phase noise in the frequency offset range of 10 Hz to 10 MHz.
Connection with a high-performance waveguide mixer (MA2806A, MA2808A) supports phase noise measurement in high frequency bands, such as the V- and E-bands.

 For more details about the Spectrum Analyzer/Signal Analyzer MS2840A, click the following links.

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