DVB-S Half-NIM Tuner Reference Design Uses the MAX2120 Tuner

2023-03-29

添加至 myAnalog

Figure 1. DVB-S Half-NIM reference design features the MAX2120 tuner

Figure 1. DVB-S Half-NIM reference design features the MAX2120 tuner.

Important Design Features:

A Popular Form Factor Often Used in the Chinese DVB-S Market; Can Be Adopted Without Physical Modifications
Active Loop-Through Using a Discrete LNA
LNB 12V Power Feed-Through

Figure 2. System block diagram.

Figure 2. System block diagram

Lab Measurements

Supply Current


Parameter	Conditions	Measured	Units
Supply Current	LNA supply 3.3V, Ta = +25°C	26	mA
Supply Current	LNA + MAX2120 3.3v, tA = +25°C	115	mA

Main Signal Path Performance

Test conditions include V_CC =+3.3V; RF input signals as specified in the following table; default register settings; and T_a = +25°C.

Parameter	Test Conditions	Frequency	Measured	Target	Units
RF Input Frequency		950 to 2150	—	—	MHz
Input Return Loss (75Ω system)	Measure at input port	—	< -6	< -6	dB
Overall Voltage Gain	Unbalanced source impedance = 75Ω, GC1 = 0.5V and GC2 = +15dB	1050MHz	91	> 80	dB
1550MHz	88
2150MHz	83
Noise Figure	GC2 = +10dB, GC1 = 0.5V	1050MHz	5.5	< 7	dB

		2150MHz	7.45
I/Q Amplitude Error	Measured at 2MHz; filter bandwidth set to 22MHz	—	0.25	< ±1	dB
I/Q Quadrature Phase Error	Measured at 2MHz; filter bandwidth set to 22MHz	—	< 2.5	< 3.5	Deg
IIP3 (In Band)	GC1 set to provide the nominal baseband output drive when mixing down a -23dBm tone at 2055MHz to 5MHz baseband (f_LO = 2050MHz). GC2 set for 7dB gain. Two tones at -26dBm each are applied at 2056MHz and 2060MHz. The IM3 tone at 2MHz is measured at baseband.	—	-1.5	-2	dBm
IIP3 (Out of Band)	GC1 set to provide the nominal baseband output drive when mixing down a -23dBm tone at 2055MHz to 5MHz baseband (f_LO = 2050MHz). GC2 set for 7dB gain. Two tones at -20dBm each are applied at f_LO -100MHz and f_LO -195MHz. The IM3 tone at 5MHz is measured at baseband.	—	10	5	dBm
IIP2 (Broadband)	GC1 set to provide the nominal baseband output drive when mixing down a -23dBm tone at 2175MHz to 5MHz baseband (f_LO = 2170MHz). GC2 set for 7dB gain. Two tones at -20dBm each are applied at 925MHz and 1250MHz. The IM2 tone at 5MHz is measured at baseband.	—	12.5	14	dBm
Phase Noise	1kHz offset, f_LO =1000MHz	—	-73.3	-70	dBc/Hz
	10kHz offset, f_LO = 1000MHz		-85.6	-82
	100kHz offset, f_LO = 1000MHz		-108.1	-102
	1MHz offset, f_LO = 1000MHz		-120.8	-122
Local Oscillator Signal Leakage at RF Input Terminal	Measured at RF input port with 50MHz increment step from 925MHz to 2175MHz	—	< -80	< -63	dBm

Loop-Through Performance


Parameter	Conditions	Measured	Target	Units
Frequency Range	925MHz to 2175MHz	--	--	MHz
Return Loss at TV_OUT	Antenna Input Terminated with 75Ω	< -6	< -6	dB
Power Gain at TV_OUT	--	-.04 to 2.8	-1 to 3	dB
Noise Figure at TV_OUT	--	< 5.5	< -6	dB
TV_OUT to ANT_IN Isolation	--	35.1	35	dB

System Performance

DVB-S system measurements for the MAX2120 Half-NIM are made by connecting to a DVB-S demodulator.

Figure 3. The DVB-S sensitivity without noise is better than -92.5dBm for 4.42Msps, and better than -84dBm for 27.5Msps across the band

Figure 3. The DVB-S sensitivity without noise is better than -92.5dBm for 4.42Msps, and better than -84dBm for 27.5Msps across the band.

Figure 4. When noise is added, the DVB-S sensitivity is better than -85dBm for 4.42Msps, and better than -77.5dBm for 27.5Msps across the band. For this case, AWGN noise is added with C/N = 5dB. For the 4.42Msps data rate, the noise bandwidth is 5.7MHz; for the 27.5Msps data rate, the noise bandwidth is 35.2MHz.

Detailed Description

This MAX2120 reference design is a compact Half-NIM DVB-S tuner for satellite STB applications. The design covers the RF range from 925MHz to 2175MHz. The MAX2120 is a fully integrated silicon tuner, which includes a LNA, RF and IF VGAs, a mixer, and a variable-bandwidth LPF in the baseband stage. The tuner is powered by a single 3.3V supply. A small number of passive components are needed to form a complete DVB-S RF front-end solution.