diff --git a/README.md b/README.md
index 38f0025..5c4ed86 100644
--- a/README.md
+++ b/README.md
@@ -41,6 +41,10 @@ The following [infinite impulse response](https://en.wikipedia.org/wiki/Infinite
 * [2n-order Butterworth cascade of second-order low or high pass filters](https://en.wikipedia.org/wiki/Butterworth_filter)
 * [second-order notch filter](https://en.wikipedia.org/wiki/Band-stop_filter)
 
+### [blockdc.hh](blockdc.hh)
+
+A [notch filter at DC](https://en.wikipedia.org/wiki/Band-stop_filter) helps removing [DC bias](https://en.wikipedia.org/wiki/DC_bias).
+
 ### [phasor.hh](phasor.hh)
 
 [Numerically controlled oscillator](https://en.wikipedia.org/wiki/Numerically_controlled_oscillator) implemented using a [phasor](https://en.wikipedia.org/wiki/Phasor) and [complex multiplication](https://en.wikipedia.org/wiki/Complex_number#Multiplication) instead of a [lookup table](https://en.wikipedia.org/wiki/Lookup_table).
diff --git a/blockdc.hh b/blockdc.hh
new file mode 100644
index 0000000..5c56f07
--- /dev/null
+++ b/blockdc.hh
@@ -0,0 +1,34 @@
+/*
+DC Blocker
+
+Copyright 2019 Ahmet Inan <inan@aicodix.de>
+*/
+
+#pragma once
+
+namespace DSP {
+
+template <typename TYPE, typename VALUE>
+class BlockDC
+{
+	TYPE x1, y1;
+	VALUE a, b;
+public:
+	constexpr BlockDC() : x1(0), y1(0), a(0), b(0.5)
+	{
+	}
+	void samples(int s)
+	{
+		a = VALUE(s - 1) / VALUE(s);
+		b = (VALUE(1) + a) / VALUE(2);
+	}
+	TYPE operator()(TYPE x0)
+	{
+		TYPE y0 = b * (x0 - x1) + a * y1;
+		x1 = x0; y1 = y0;
+		return y0;
+	}
+};
+
+}
+