diff --git a/rf-analyzer/rf-analyzer-cache.lib b/rf-analyzer/rf-analyzer-cache.lib
index ea5965747c06f063175f9d4871ba6946ae4befe4..d2b79264432629ddd1af4ebf25b67f0caafffe12 100644
--- a/rf-analyzer/rf-analyzer-cache.lib
+++ b/rf-analyzer/rf-analyzer-cache.lib
@@ -26,6 +26,27 @@ X DIS ?? 0 300 200 D 50 50 2 1 I
 ENDDRAW
 ENDDEF
 #
+# Amplifier_Operational_Freemo_TLV3501_DBV
+#
+DEF Amplifier_Operational_Freemo_TLV3501_DBV U 0 10 Y Y 1 F N
+F0 "U" 100 250 50 H V L CNN
+F1 "Amplifier_Operational_Freemo_TLV3501_DBV" 0 -150 50 H V L CNN
+F2 "Package_TO_SOT_SMD:SOT-23-6" 650 -250 50 H I C CNN
+F3 "" 100 250 50 H I C CNN
+$FPLIST
+ SOT-23-6
+$ENDFPLIST
+DRAW
+P 4 0 1 10 -200 200 200 0 -200 -200 -200 200 f
+X V- 2 -100 -300 150 U 50 50 0 1 W
+X V+ 4 -100 300 150 D 50 50 0 1 W
+X - 1 -300 -100 100 R 50 50 1 1 I
+X + 3 -300 100 100 R 50 50 1 1 I
+X ~ 5 300 0 100 L 50 50 1 1 O
+X SHDN 6 0 -300 200 U 50 50 1 1 I
+ENDDRAW
+ENDDEF
+#
 # Analog_ADC_LTC2309_TSSOP
 #
 DEF Analog_ADC_LTC2309_TSSOP U 0 40 Y Y 1 F N
@@ -126,6 +147,28 @@ X A 2 100 0 70 L 50 50 1 1 P
 ENDDRAW
 ENDDEF
 #
+# Device_D_Zener
+#
+DEF Device_D_Zener D 0 40 N N 1 F N
+F0 "D" 0 100 50 H V C CNN
+F1 "Device_D_Zener" 0 -100 50 H V C CNN
+F2 "" 0 0 50 H I C CNN
+F3 "" 0 0 50 H I C CNN
+$FPLIST
+ TO-???*
+ *_Diode_*
+ *SingleDiode*
+ D_*
+$ENDFPLIST
+DRAW
+P 2 0 1 0 50 0 -50 0 N
+P 3 0 1 10 -50 -50 -50 50 -30 50 N
+P 4 0 1 10 50 -50 50 50 -50 0 50 -50 N
+X K 1 -150 0 100 R 50 50 1 1 P
+X A 2 150 0 100 L 50 50 1 1 P
+ENDDRAW
+ENDDEF
+#
 # Device_R_Small
 #
 DEF Device_R_Small R 0 10 N N 1 F N
diff --git a/rf-analyzer/rf-analyzer.sch b/rf-analyzer/rf-analyzer.sch
index 25aa19986764568c4cd979b708e4b5d177386b54..023c539ac22b79ccb6f499436b6ba0b0af061c41 100644
--- a/rf-analyzer/rf-analyzer.sch
+++ b/rf-analyzer/rf-analyzer.sch
@@ -1319,7 +1319,7 @@ Wire Wire Line
 	9500 5700 9450 5700
 Wire Wire Line
 	9450 5700 9450 5800
-Text GLabel 6350 5000 2    50   Input ~ 0
+Text GLabel 6650 3750 2    50   Input ~ 0
 freq_count
 $Comp
 L arduino:Arduino_Due_Shield XA?
@@ -1586,4 +1586,152 @@ Connection ~ 1200 7350
 Wire Wire Line
 	1200 7250 1200 7150
 Connection ~ 1200 7250
+$Comp
+L Device:C_Small C?
+U 1 1 604F0B98
+P 5100 3850
+F 0 "C?" V 4900 3800 50  0000 L CNN
+F 1 "1nF" V 5000 3750 50  0000 L CNN
+F 2 "Capacitor_SMD:C_0603_1608Metric_Pad1.05x0.95mm_HandSolder" H 5100 3850 50  0001 C CNN
+F 3 "" H 5100 3850 50  0001 C CNN
+	1    5100 3850
+	0    1    1    0   
+$EndComp
+$Comp
+L power:+3.3V #PWR?
+U 1 1 60554C94
+P 5900 3400
+F 0 "#PWR?" H 5900 3250 50  0001 C CNN
+F 1 "+3.3V" H 5915 3573 50  0000 C CNN
+F 2 "" H 5900 3400 50  0001 C CNN
+F 3 "" H 5900 3400 50  0001 C CNN
+	1    5900 3400
+	1    0    0    -1  
+$EndComp
+$Comp
+L power:GNDA #PWR?
+U 1 1 605777A2
+P 5450 3600
+F 0 "#PWR?" H 5450 3350 50  0001 C CNN
+F 1 "GNDA" H 5455 3427 50  0000 C CNN
+F 2 "" H 5450 3600 50  0001 C CNN
+F 3 "" H 5450 3600 50  0001 C CNN
+	1    5450 3600
+	1    0    0    -1  
+$EndComp
+$Comp
+L Device:R_Small R?
+U 1 1 60590B3F
+P 5300 3350
+F 0 "R?" V 5200 3300 50  0000 L CNN
+F 1 "1KΩ" V 5400 3250 50  0000 L CNN
+F 2 "Resistor_SMD:R_0603_1608Metric_Pad1.05x0.95mm_HandSolder" H 5300 3350 50  0001 C CNN
+F 3 "" H 5300 3350 50  0001 C CNN
+	1    5300 3350
+	0    1    1    0   
+$EndComp
+$Comp
+L Amplifier_Operational_Freemo:TLV3501_DBV U?
+U 1 1 5F57AB43
+P 6000 3750
+F 0 "U?" H 6150 4000 50  0000 L CNN
+F 1 "TLV3501_DBV" H 6000 3900 50  0000 L CNN
+F 2 "Package_TO_SOT_SMD:SOT-23-6" H 6650 3500 50  0001 C CNN
+F 3 "" H 6100 4000 50  0001 C CNN
+	1    6000 3750
+	1    0    0    -1  
+$EndComp
+$Comp
+L Device:C_Small C?
+U 1 1 5F5C5A9B
+P 5450 3450
+F 0 "C?" V 5250 3400 50  0000 L CNN
+F 1 "100nF" V 5350 3350 50  0000 L CNN
+F 2 "Capacitor_SMD:C_0603_1608Metric_Pad1.05x0.95mm_HandSolder" H 5450 3450 50  0001 C CNN
+F 3 "" H 5450 3450 50  0001 C CNN
+	1    5450 3450
+	-1   0    0    1   
+$EndComp
+Wire Wire Line
+	5450 3600 5450 3550
+Wire Wire Line
+	5400 3350 5450 3350
+Wire Wire Line
+	5450 3350 5700 3350
+Wire Wire Line
+	5700 3350 5700 3650
+Connection ~ 5450 3350
+Wire Wire Line
+	5200 3350 5200 3850
+Wire Wire Line
+	5200 3850 5700 3850
+Connection ~ 5200 3850
+$Comp
+L power:GNDA #PWR?
+U 1 1 5F68DE6E
+P 5900 4100
+F 0 "#PWR?" H 5900 3850 50  0001 C CNN
+F 1 "GNDA" H 5905 3927 50  0000 C CNN
+F 2 "" H 5900 4100 50  0001 C CNN
+F 3 "" H 5900 4100 50  0001 C CNN
+	1    5900 4100
+	1    0    0    -1  
+$EndComp
+Wire Wire Line
+	5900 4050 5900 4100
+Wire Wire Line
+	6000 4050 6000 4100
+Wire Wire Line
+	6000 4100 5900 4100
+Connection ~ 5900 4100
+Wire Wire Line
+	5900 3400 5900 3450
+Text GLabel 4950 3850 0    60   Input ~ 0
+fwd_sig_dc
+Wire Wire Line
+	4950 3850 5000 3850
+$Comp
+L Device:R_Small R?
+U 1 1 5F77CD96
+P 6450 3750
+F 0 "R?" V 6350 3700 50  0000 L CNN
+F 1 "170Ω" V 6550 3650 50  0000 L CNN
+F 2 "Resistor_SMD:R_0603_1608Metric_Pad1.05x0.95mm_HandSolder" H 6450 3750 50  0001 C CNN
+F 3 "" H 6450 3750 50  0001 C CNN
+	1    6450 3750
+	0    1    1    0   
+$EndComp
+$Comp
+L Device:D_Zener D?
+U 1 1 5F7D1F53
+P 6600 3950
+F 0 "D?" V 6600 3800 50  0000 L CNN
+F 1 "3.3v" V 6700 3750 50  0000 L CNN
+F 2 "" H 6600 3950 50  0001 C CNN
+F 3 "~" H 6600 3950 50  0001 C CNN
+	1    6600 3950
+	0    1    1    0   
+$EndComp
+$Comp
+L power:GNDA #PWR?
+U 1 1 5F7D93FA
+P 6600 4150
+F 0 "#PWR?" H 6600 3900 50  0001 C CNN
+F 1 "GNDA" H 6605 3977 50  0000 C CNN
+F 2 "" H 6600 4150 50  0001 C CNN
+F 3 "" H 6600 4150 50  0001 C CNN
+	1    6600 4150
+	1    0    0    -1  
+$EndComp
+Wire Wire Line
+	6300 3750 6350 3750
+Wire Wire Line
+	6550 3750 6600 3750
+Wire Wire Line
+	6600 3750 6600 3800
+Wire Wire Line
+	6600 4100 6600 4150
+Wire Wire Line
+	6650 3750 6600 3750
+Connection ~ 6600 3750
 $EndSCHEMATC